Samoa Cookie Sheet Cake

This cake is out of this world delicious! It is a decadent moist chocolate cake with a baked buttery shortbread crust that is infused with sweetened condensed milk and caramel sauce. It is then topped off with a caramel Swiss meringue buttercream, toasted shredded coconut, caramel sauce, chocolate ganache, & Girl Scout Samoa Cookies (optional but a bonus if you have them) or you can always use Keebler Coconut Dream Cookies.

This recipe is made with store bought cake mix to make your life a little bit easier, but if store bought cake mixes are not your jam you can use my chocolate sheet cake recipe. Also, if you wanted to make cupcakes, a bundt cake, or a 2 layered cake out of this recipe please see my FAQs section below for all the details on baking temperatures and times for those.

WHAT YOU NEED TO MAKE THIS CHOCOLATE SHORTBREAD COOKIE SHEET CAKE

• Chocolate Cake Box Mix: Any brand of chocolate cake box mix will do.
• Shortbread Cookies: I like using Lorna Doone shortbread cookies, but you may use a different kind of shortbread cookie. You’ll need at least 10 ounces.
• Pure Vanilla Extract: Gives flavor! I get my favorite pure vanilla extract from Costco.
• Butter: Melted. I recommend using unsalted butter.
• Buttermilk: Make sure you bring the milk to room temperature. Avoid lower fat or nonfat milks. Milk with fat will give you the best flavor and add moisture to the cake. If you don’t have buttermilk, you can make a DIY sour milk substitute. Add 2 teaspoons of white vinegar or lemon juice to a liquid measuring cup. Then add enough whole milk to the same measuring cup until it reaches 1 cup. (In a pinch, lower fat or nondairy milks work for this soured milk, but the cake won’t taste as moist or rich.) Stir it around and let sit for 5 minutes. The homemade “buttermilk” will be somewhat curdled and ready to use in the recipe.
• Sour Cream: Makes cakes moist! Make sure sour cream is at room temperature. I would suggest removing from the fridge an hour or so ahead of time.
• Avocado Oil: Since cocoa powder is a particularly drying ingredient this cake needs oil for suitable moisture. You can also use vegetable oil, canola oil or melted coconut oil.
• Unsweetened Cocoa Powder: Use natural cocoa powder in the cake, not dutch-process.
• Eggs: Make sure you bring the eggs to room temperature so they can effortlessly mix into the batter without over mixing.
• Shredded Sweetened Coconut: Unsweetened shredded coconut would work too.

• Sweetened Condensed Milk

• Girl Scout Samoa Cookies (optional): For decorating the sheet cake. You can also use Keebler Coconut Dream Cookies if you can’t get your hands on the Girl Scout Samoa Cookies.

WHAT INGREDIENTS YOU NEED TO MAKE CARAMEL SWISS MERINGUE BUTTERCREAM

• Granulated Sugar
• Salt
• Eggs Whites: At room temperature.
• Butter: Unsalted and at room temperature. I recommend using unsalted butter because you are able to control the amount of salt you want especially when making the frosting. Be sure to bring the butter to room temperature. I always take mine out a couple hours before I want to bake. It must be soft enough so your finger leaves a dent when pressing it. If you forget to take your butter out, you can zap it in the microwave for about 20 seconds. Do not melt the butter completely.
• Vanilla Extract
• Caramel Sauce: Homemade or store bought.

WHAT INGREDIENTS YOU NEED TO MAKE HOMEMADE CARAMEL SAUCE

• Granulated Sugar
• Butter: Unsalted and at room temperature cut into 6 pieces.
• Heavy Cream: Light whipping cream (30% milk fat) or double cream (48% milk fat) may be substituted. Do not use milk.
• Salt: Any variety of salt will work. You can always add 3/4 teaspoon, taste, then add more if desired. If you want to make regular caramel, reduce salt to 1/2 teaspoon.

WHAT INGREDIENTS YOU NEED TO MAKE CHOCOLATE GANACHE

• Heavy Cream
• Chocolate Chips: I love using Guittard milk chocolate chips.

WHAT SUPPLIES YOU NEED

• 9×13 Inch Pan: Metal, glass or disposable pan is fine. Either will do. I love using Fat Daddio pans.
• Offset Icing Spatula. You can find one on Amazon.
• Food Processor
• Pipping bags: I get mine from Amazon.
• Pipping tips: 4B or 8B (which is what I used).  I get mine from Michaels.
• Thermometer (optional): I like using a thermometer to make the Swiss meringue buttercream.

HOW TO MAKE CHOCOLATE SHEET CAKE

Preheat the oven to 325°F. Generously grease a 9×13 inch cake pan.

In a food processor, blend up the shortbread cookies until a fine powder forms. Add in the melted butter and stir until combined. Press the crust in the prepared baking pan and press firmly in an even layer with the bottom of a cup. Bake for 10 minutes. Set aside.

In a large bowl, whisk together the buttermilk, sour cream, eggs, oil, and vanilla until combined.

Mix in the unsweetened cocoa powder and cake box mix.

Whisk until throughly combined.

Pour the batter into the prepared pan. Bake for 27-30 minutes or until a toothpick inserted in the center comes out clean. Baking times vary, so keep an eye on yours.

Note: The cooled cake may slightly sink in the center. Cocoa powder is simply not as structurally strong as all-purpose flour and can’t hold up to all the moisture necessary to make a moist tasting chocolate cake.

Remove from the oven and allow the cake to cool in the pan. Cool completely before decorating. As the cake is cooling, make the caramel sauce, chocolate ganache, caramel Swiss meringue buttercream, & toast the shredded coconut.

Tip: I like placing my cakes covered in the refrigerator or freezer while I make my frostings and/or toppings. I do this so that when I spread the frosting on the cold cake, the cake doesn’t pull away and I have no issues with crumbs in the frosting.

Heat sugar in a medium saucepan over medium heat, whisking constantly with a high heat-resistant rubber spatula or wooden spoon. Sugar will form clumps and eventually melt into a thick brown, amber-colored liquid as you continue to stir. Make sure you stay close by and keep an eye out because it can burn quickly.

Once sugar is completely melted, carefully add the butter. Whisk the butter into the caramel until it is completely melted, about 2 minutes. The caramel will bubble rapidly when the butter is added so be careful as it may splatter a bit.

Next, slowly and carefully drizzle in the heavy cream while whisking. Since the heavy cream is colder than the hot caramel, the mixture will rapidly bubble when added. Allow the mixture to boil for 1 minute.

Remove from heat and stir in 2 teaspoons of salt. The caramel will be a thin liquid but it will thicken as it cools. Allow to slightly cool down before using.

Cover tightly and store for up to 1 month in the refrigerator. You will need to reheat the caramel before using in the microwave or on the stove top as caramel solidifies in the refrigerator.

Makes about 2 cups of caramel sauce.

HOW TO MAKE CHOCOLATE GANACHE

Place chocolate chips and heavy cream in a microwave-safe bowl and microwave for 30 seconds.

Stir well, and then return to microwave and heat in 15-second increments, stirring well in between, until chocolate is completely melted and smooth. Set aside.

HOW TO MAKE CARAMEL SWISS MERINGUE BUTTERCREAM

Add egg whites, sugar and salt in a glass bowl. Give the mixture a brief whisk.

Place the glass bowl over a pan of simmering water. Make sure the water does not touch the glass bowl.

Whisk the egg whites occasionally while it warms up. When the mixture has warmed, whisk it constantly. You will heat the mixture until it reaches an internal temperature of 160ºF or until it’s not grainy between your fingers.

Carefully transfer the mixture from the glass bowl to a stand mixer, mix with a whisk attachment until you get room temperature glossy peaks.

You can switch to a paddle attachment and while the mixture is running on low, add tablespoon sized dollops of room temperature butter making sure to let the butter incorporate before you add the next piece.

Once all the butter is incorporated, go ahead and add the vanilla extract and about 1/2 cup of caramel sauce.

Tips for making Swiss Meringue Buttercream

• If your equipment or bowl has grease on it, wipe down everything with lemon juice or vinegar. It is essential to have a clean and dry bowl for whipping the egg whites.
• The egg whites cannot contain any egg yolk. Egg yolks prevent your meringue from setting up.
• It is okay if it looks soupy or curdled after adding the butter. Don’t fret, just continue to let it whip, and it’ll come together at the end. If the mixture does not come together and stays curdled after 5 to 10 minutes, you can place the mixing bowl over a simmering pot to let the edges of the meringue warm up before continuing to mix it.

HOW TO TOAST SHREDDED COCONUT

On the stove: Pour shredded coconut into a medium skillet. Turn the stove on low to medium heat and stir often. It will take five to seven minutes for the coconut to turn light brown.

In theOven: Preheat oven to 325°F. Line a rimmed baking sheet with parchment paper. Spread coconut in an even layer in the parchment paper-lined sheet. Toast 8 to 10 minutes, stirring 2 to 3 times, or until the coconut is golden brown.

HOW TO DECORATE THE CAKE

Pour and spread the condensed milk over the cake with a spatula or the back of a spoon.

Next, drizzle 3/4 cup of caramel sauce over the top.

Cool the cake to room temperature and then refrigerate for at least 2 hours, or cover and chill overnight.

Evenly spread the caramel Swiss meringue buttercream over the top of the cake using an icing spatula (or back of a spoon). I used about 2 cups of frosting.

Spread the toasted shredded coconut over the buttercream.

Drizzle the caramel sauce over the coconut.

Drizzle the chocolate ganache over the caramel sauce.

Using a pipping bag filled with caramel Swiss meringue buttercream and a 4B or 8B (is what I used) pipping tip, pipe the design (see below) evenly all the way around the pan.

Optional: Top the cake off with Girl Scout Samoa Cookies!

Slice into 12 servings. (Tip: To easily & cleanly cut through the cake, use a hot knife by running it through hot water & drying it off with a towel).

Cover leftovers tightly and store in the refrigerator for up to 3 days.

TIPS FOR MAKING THIS RECIPE

• Do not over-mix the batter as you risk over-developing the gluten leading to a tough, dry, and dense cake.
• All refrigerated items should be at room temperature so the batter mixes together easily and evenly.
• Make sure to allow the cake to cool before you add the buttercream.
• Make sure the butter is room temperature before you cream it, as cold butter will lead to lumpy buttercream.
• The longer you chill the cake, the better the buttercream will stick to the cake layers.

FREQUENTLY ASKED QUESTIONS

Can I make this cake in advance?

Yes! You can make the cake, caramel sauce, chocolate ganache, caramel Swiss merginue buttercream, and toasted coconut a few days ahead of time and keep them tightly wrapped in the fridge, then assemble them when you’re ready. You can also make the entire cake in advance, wrap and place it in the fridge for up to 3 days.

I don’t like cake box mix, can I use a homemade sheet cake recipe?

Yes! You can use my chocolate sheet cake recipe.

Can I make the caramel sauce ahead of time?

Yes! Cover and store it for up to 1 month in the refrigerator. Once you are ready to use just zap it in the microwave few seconds or warm it up on the stove top. You can freeze in an airtight container for up to 3 months. Thaw in the refrigerator or at room temperature, then warm up before using.

Can I make this with store bought caramel sauce?

Sure, why not!?

Can I make the chocolate ganache ahead of time?

Yep! You can store in the refrigerator for about a week. Just zap in the microwave for about 15 seconds or so to get it to a spreadable consistency.

Can I make this with store bought chocolate sauce?

Absolutely!

Can I make the Caramel Swiss Meringue buttercream ahead of time?

Yes! You can refrigerate it for up to 5 days or freeze up to 3 months. If freezing, store in an airtight container, then thaw it at room temperature on the counter.

Can I turn this recipe into a 2 layer cake?

Yes! Grease two 8 or 9 inch round cake pans (which ever size you have on hand), line with parchment paper rounds, then grease the parchment paper. Parchment paper helps the cakes seamlessly release from the pans. Divide the cookie base and batter evenly between the pans. Bake time will be a few minutes shorter—keep a close eye and check for doneness with a toothpick. Once baked leaving the cakes in the pans, poke holes and drizzle the cake with the sweetened condensed milk and caramel sauce. Refrigerate for a few hours. Assemble the cake with a layer of caramel Swiss meringue buttercream, toasted shredded coconut, caramel sauce, and chocolate ganache. Frost the outside of the cake with the caramel Swiss meringue buttercream and you can decorate with the leftover toasted shredded coconut, caramel sauce, chocolate ganache and Girl Scout Samoa Cookies.

Can I turn this recipe into a bundt cake?

Yes! Grease your bundt pan with. Bake time will be a few minutes longer—keep a close eye and check for doneness with a toothpick. Once baked remove the cake from the pan and place on a serving plate. Poke holes and drizzle the cake with the sweetened condensed milk and caramel sauce. Refrigerate for a few hours. To decorate frost the bundt cake with the caramel Swiss meringue buttercream, then sprinkle on the toasted shredded coconut and drizzle on the caramel sauce and chocolate ganache. You can decorate the sides by placing the Girl Scout Samoa Cookies around the cake.

Can I turn this recipe into cupcakes?

Yes! Using a cupcake pan fill cupcake liners with about a tablespoon of the cookie base and then 2/3 full of batter. I love using this baking scoop for my regular sized cupcakes and this baking scoop and mini cupcake liners for my mini cupcakes. Bake at 350°F for 18-21 minutes. Yields about 2-3 dozen regular sized cupcakes. Once baked, you can poke holes and drizzle each cupcake with the sweetened condensed milk and caramel sauce. Refrigerate for a few hours. Top each cupcake with caramel Swiss meringue buttercream, toasted coconut, caramel sauce, chocolate ganache, and a Girl Scout Samoa Cookie.

How do I store cake leftovers? 

Cover and store leftover cake in the refrigerator for up to 3 days. You can also freeze the cake for up to 3 months. If you plan to freeze this cake bake it in a foil pan. Wrap the finished cake tightly in plastic wrap and aluminum foil. Thaw overnight in the refrigerator.

Make sure you post your photos on Instagram and tag me in them so I can see your creations from my blog #eazypeazylemonsqueezee

Samoa Cookie Sheet Cake

Level: Beginner

By: Tammie

• March 29, 2024
• 12
• 4 hr
• Count the memories not the calories! Cals/Serving
• Print this

Ingredients

• Chocolate Shortbread Cookie Cake:
• Shortbread cookies (10 ounces), pulsed to a powder in a food processor
• 4 tablespoons unsalted butter, melted
• 3/4 cup buttermilk, at room temperature
• 2/3 cup sour cream, at room temperature
• 3 eggs, at room temperature
• 1/3 cup oil (avocado oil, vegetable oil, canola oil or melted coconut oil)
• 1 Tablespoon pure vanilla extract
• 1/2 unsweetened natural cocoa powder
• 1 box chocolate cake mix
• 1-14oz can sweetened condensed milk
• 3/4 cup of caramel sauce, homemade or store bought
• Caramel Swiss Meringue Buttercream:
• 5 egg whites, at room temperature
• 2 cups (4 sticks) unsalted butter, at room temperature
• 1 and 1/2 cups granulated sugar
• 1/8 teaspoon salt
• 1 teaspoon vanilla extract
• 1/2 cup caramel sauce
• Caramel Sauce:
• 2 cups granulated sugar
• 12 tablespoons unsalted butter, room temperature cut up into 12 pieces
• 1 cup heavy cream
• 2 teaspoons salt
• Chocolate Ganache:
• 1 cup chocolate chips
• 1/2 cup heavy cream
• Toppings:
• 14 ounces of shredded sweetened coconut, toasted
• Caramel sauce, homemade or store bought
• Chocolate ganache, homemade or store bought
• Girl Scout Samoa Cookies or Keebler Coconut Dream Cookies (optional)
• Supplies:
• 9x13 inch sheet pan
• Offset Icing Spatula
• Pipping bags
• Pipping tips 4B or 8B
• Food Processor
• Thermometer (optional)

Directions

Step 1

PREP CAKE: Preheat the oven to 325°F. Generously grease a 9×13 inch cake pan.

Step 2

SHORTBREAD COOKIE CRUST: In a food processor, blend up the shortbread cookies until a fine powder forms. Add in the melted butter and stir until combined. Press the crust in the prepared baking pan and press firmly in an even layer with the bottom of a cup. Bake for 10 minutes. Set aside.

Step 3

WET INGREDIENTS: In a large bowl, whisk together the buttermilk, sour cream, eggs, oil, and vanilla until combined.

Step 4

COMBINE: Mix in the unsweetened cocoa powder and cake box mix. Whisk until throughly combined.

Step 5

BAKE: Pour the batter into the prepared pan. Bake for 27-30 minutes or until a toothpick inserted in the center comes out clean. Baking times vary, so keep an eye on yours. (Note: The cooled cake may slightly sink in the center. Cocoa powder is simply not as structurally strong as all-purpose flour and can’t hold up to all the moisture necessary to make a moist tasting chocolate cake). Remove from the oven and allow the cake to cool in the pan. Cool completely before decorating. As the cake is cooling, make the caramel sauce, chocolate ganache, caramel Swiss meringue buttercream, & toast the shredded coconut. (Tip: I like placing my cakes covered in the refrigerator or freezer while I make my frostings and/or toppings. I do this so that when I spread the frosting on the cold cake, the cake doesn’t pull away and I have no issues with crumbs in the frosting.)

Step 6

FOR THE FROSTING: Add egg whites, sugar and salt in a glass bowl. Give the mixture a brief whisk. Place the glass bowl over a pan of simmering water. Make sure the water does not touch the glass bowl. Whisk the egg whites occasionally while it warms up. When the mixture has warmed, whisk it constantly. You will heat the mixture until it reaches an internal temperature of 160ºF or until it’s not grainy between your fingers. Carefully transfer the mixture from the glass bowl to a stand mixer, mix with a whisk attachment until you get room temperature glossy peaks. Switch to a paddle attachment and while the mixture is running on low, add tablespoon sized dollops of room temperature butter making sure to let the butter incorporate before you add the next piece. Once all the butter is incorporated, go ahead and add the vanilla extract and about 1/2 cup of caramel sauce. Swiss Meringue Buttercream tips are above recipe.

Step 7

FOR THE CARAMEL SAUCE: Heat sugar in a medium saucepan over medium heat, whisking constantly with a high heat-resistant rubber spatula or wooden spoon. Sugar will form clumps and eventually melt into a thick brown, amber-colored liquid as you continue to stir. Make sure you stay close by and keep an eye out because it can burn quickly. Once sugar is completely melted, carefully add the butter. Whisk the butter into the caramel until it is completely melted, about 2 minutes. The caramel will bubble rapidly when the butter is added so be careful as it may splatter a bit. Next, slowly and carefully drizzle in the heavy cream while whisking. Since the heavy cream is colder than the hot caramel, the mixture will rapidly bubble when added. Allow the mixture to boil for 1 minute. Remove from heat and stir in 2 teaspoons of salt. The caramel will be a thin liquid but it will thicken as it cools. Allow to slightly cool down before using. Cover tightly and store for up to 1 month in the refrigerator. You will need to reheat the caramel before using in the microwave or on the stove top as caramel solidifies in the refrigerator.

Step 8

FOR THE CHOCOLATE GANACHE: Place chocolate chips and heavy cream in a microwave-safe bowl and microwave for 30 seconds. Stir well, and then return to microwave and heat in 15-second increments, stirring well in between, until chocolate is completely melted and smooth. Set aside.

Step 9

TOAST SHREDDED COCONUT: On the stove: Pour shredded coconut into a medium skillet. Turn the stove on low to medium heat and stir often. It will take five to seven minutes for the coconut to turn light brown. In the Oven: Preheat oven to 325°F. Line a rimmed baking sheet with parchment paper. Spread coconut in an even layer in the parchment paper-lined sheet. Toast 8 to 10 minutes, stirring 2 to 3 times, or until the coconut is golden brown.

Step 10

DECORATE THE CAKE: Using a wooden skewer or fork, poke holes all over the cake. When poking the holes in the cake, make sure not to poke through to the bottom. You don’t want the condensed milk and caramel to leak out the bottom. Pour and spread the condensed milk over the cake with a spatula or the back of a spoon. Next, drizzle 3/4 cup of caramel sauce over the top. Cool the cake to room temperature and then refrigerate for at least 2 hours, or cover and chill overnight. Evenly spread the caramel Swiss meringue buttercream over the top of the cake using an icing spatula (or back of a spoon). I used about 2 cups of frosting. Spread the toasted shredded coconut over the buttercream. Drizzle the caramel sauce over the coconut. Drizzle the chocolate ganache over the caramel sauce. Using a pipping bag filled with caramel Swiss meringue buttercream and a 4B or 8B (is what I used) pipping tip, pipe the design (see above) evenly all the way around the pan. Optional: Top the cake off with Girl Scout Samoa Cookies! Slice into 12 servings. (Tip: To easily & cleanly cut through the cake, use a hot knife by running it through hot water & drying it off with a towel).

Step 11

Cover leftovers tightly and store in the refrigerator for up to 3 days.