Doctored Vanilla Sheet Cake

Doctored store bought vanilla cake mix is a great option for so many reasons. Maybe you don’t bake all that much so you don’t have all the ingredients on hand and don’t want to spend a ton of money just to make a cake every once in awhile. Maybe you’re short on time or just maybe you hate baking. Sometimes store boxed cake mix and frosting is the way to go. Even though I prefer to make my cakes and frostings from scratch, there is no judgment here if you don’t.

Along with this doctored vanilla cake recipe, I have included my vanilla bean buttercream recipe to frost this vanilla cake, but you are more than welcome to use store bought frosting or another buttercream flavor instead. I have also included a little tutorial on how you can decorate this sheet cake, but again this is totally optional. You can decorate how ever you please! 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 DOCTORED VANILLA CAKE

White Cake Box Mix: Any brand of white cake box mix will do.
Pure Vanilla Extract: Gives flavor! I get my favorite pure vanilla extract from Costco.
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: You can also use vegetable oil, canola oil or melted coconut oil.
Eggs: Make sure you bring the eggs to room temperature so they can effortlessly mix into the batter without over mixing.
Sprinkles & Edible Glitter (optional): I used Fancy Sprinkles edible gold glitter.

WHAT INGREDIENTS YOU NEED TO MAKE VANILLA BEAN BUTTERCREAM

Butter: 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 forgot to take your butter out to come out to room temperature you can also zap it in the microwave for about 20 seconds. Do not melt the butter completely.
Salt: Adds flavor. I like using sea salt or pink Himalayan salt.
Pure Vanilla Extract & Vanilla Bean Paste: Vanilla bean paste is a game changer in recipes. If you do not have vanilla bean paste it’s not the end of the world, you can substitute with pure vanilla extract. My favorite brand for vanilla bean paste is Nielsen-Massey and you can find it on Amazon. I believe Trader Joe’s also sells their own vanilla bean paste too!
Heavy Cream: You can also use whole milk if you do not have heavy cream on hand.
Powdered Sugar: Also called confectioners sugar. PS- you do not need to sift it!

WHAT SUPPLIES YOU NEED

9×13 Inch Pan: Metal, glass or disposable pan is fine. Either will do. I love using Fat Daddio pans.
Pipping Bags (optional): I get mine from Amazon.
Pipping Tips (optional): 1M, 4B, 8B and 102. I get mine from Michaels.

HOW TO MAKE A DOCTORED VANILLA SHEET CAKE

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

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

Mix in the cake box mix. Whisk until throughly combined.

Pour the batter into the prepared pan.

Bake for 27 to 30 minutes or until a toothpick inserted in the center comes out clean. Baking times vary, so keep an eye on yours.

Remove from the oven and allow the cake to cool in the pan. Cool completely before decorating. As the cake is cooling, you can make the frosting or other ingredients you may need to decorate the cake.

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.

HOW TO MAKE VANILLA BUTTERCREAM

Using a hand-held mixer or stand mixer fitted with a paddle or whisk attachment, beat the butter on medium speed until light and fluffy, about 2 minutes. Add vanilla extract, vanilla bean paste, heavy cream and salt with the mixer running on low. Slowly add the powdered sugar. Increase to high speed and beat for 3 full minutes. You can add more powdered sugar if frosting is too thin, more cream if the frosting is too thick, or a little more of salt if the frosting is too sweet. Yields about 6 cups of frosting.

HOW TO DECORATE THE CAKE

Using a pipping bag filled with vanilla buttercream (about 1 cup) and a 1M pipping tip, pipe rosettes (see below) in random places on the cake.

With another pipping bag filled with vanilla buttercream (about 1 cup) and a 8B pipping tip, pipe the design (see below) in random places on the cake.

With another pipping bag filled with vanilla buttercream (about 1 cup) and a 102 pipping tip, pipe the design (see below) in random places on the cake.

With another pipping bag filled with vanilla buttercream (about 1 cup) and a 4B pipping tip, pipe the design (see below) in the open spots on the cake.

If you’d like to take your decorating up a notch add sprinkles and/or gold edible glitter like it did. I suggest doing this right after you finishing piping so they can stick to the frosting.

Slice and serve. Cover leftovers tightly and store in the refrigerator for up to 5 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 and buttercream frosting a few days ahead of time and keep them tightly wrapped in the fridge, then assemble them when you’re ready. You will need to pull out your buttercream from the refrigerator a few hours before you’d like to decorate to bring it back to a spreadable consistency. I would suggest once the buttercream has softened whip it up in your mixer before adding it to your pipping bags to decorate. You can also make the entire cake in advance, wrap and place it in the fridge for up to 5 days.

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 batter evenly between the pans. Bake at 325°F for about 27 to 30 minutes—keep a close eye on the cakes and check for doneness with a toothpick.

Can I turn this recipe into a bundt cake?

Yes! Grease your bundt pan with. Bake at 325°F for about 25 to 35 minutes—keep a close eye on the cake and check for doneness with a toothpick.

Can I turn this recipe into cupcakes?

Yes! Using a cupcake pan fill cupcake liners 2/3 full. 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 about 14 to 19 minutes. Yields about 22 regular sized cupcakes.

Can I make this with store bought frosting?

Yes! You can use any vanilla store bought frosting. I would suggest using up 2 to 4 containers of the store bought frosting. Proceed to Step 6 on directions on how to decorate the cake.

Do I have to decorate it they way you did?

Of course not! If you think the way I designed this cake is too hard or not to your liking then be my guest to recreate your own design. You do you boo!

How do I store leftover frosting?

Buttercream frosting can be stored in the refrigerator for at least seven days. Just be sure that the container is tightly sealed and that you keep the frosting far from pungent foods like seafood since the smells can transfer. You can also freeze buttercream frosting for up to 3 months in an airtight container or freezer bag. The day before you’re ready to use it, let it thaw in the refrigerator overnight, then bring it to room temperature before re-whipping again. This is helpful if you’re making buttercream months in advance, or you have leftover frosting you’d like to use later on.

How do I store cake leftovers?

Cover and store leftover cake at room temperature for up to 3 days or refrigerate for up to 5 days. You can also freeze frosted cake or unfrosted cake can be frozen up to 2-3 months. Make sure to throughly wrap with plastic wrap and aluminum foil. Thaw overnight in the refrigerator and bring to room temperature before decorating/serving.

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

Level: Beginner

By: Tammie

February 14, 2024
12
4 hr
Count the memories not the calories! Cals/Serving
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Ingredients

Vanilla Cake:
3/4 cup buttermilk, room temperature
2/3 cup sour cream, room temperature
1/3 cup oil (avocado oil, vegetable oil, canola oil or melted coconut oil)
4 egg whites, at room temperature
1 Tablespoon pure vanilla extract
1 white cake box mix
Vanilla Bean Buttercream:
1 and 1/2 cups (3 sticks) unsalted butter, at room temperature
1 Tablespoon pure vanilla extract
1 Tablespoon vanilla bean paste
1/4 teaspoon salt
1/2 cup heavy cream
2 lbs powdered sugar (1 bag)
Toppings (optional):
Sprinkles
Edible glitter
Supplies:
9x13 inch sheet pan
Pipping bags (optional)
Pipping tips: 1M, 4B, 8B & 102 petal (optional)

Directions

Step 1: PREP CAKE: Preheat the oven to 325°F. Generously grease a 9×13 inch cake pan.
Step 2: WET INGREDIENTS: In a large bowl, whisk together the buttermilk, sour cream, eggs, oil, and vanilla until combined.
Step 3: COMBINE: Mix in the cake box mix. Whisk until throughly combined.
Step 4: BAKE: Pour the batter into the prepared pan. Bake for 27 to 30 minutes or until a toothpick inserted in the center comes out clean. Baking times vary, so keep an eye on yours. Remove from the oven and allow the cake to cool in the pan. Cool completely before decorating. As the cake is cooling, you can make the frosting or other ingredients you may need to decorate the cake. 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 5: MAKE VANILLA BEAN BUTTERCREAM: Using a hand-held mixer or stand mixer fitted with a paddle or whisk attachment, beat the butter on medium speed until light and fluffy, about 2 minutes. Add vanilla extract, vanilla bean paste, heavy cream and salt with the mixer running on low. Slowly add the powdered sugar. Increase to high speed and beat for 3 full minutes. You can add more powdered sugar if frosting is too thin, more cream if the frosting is too thick, or a little more of salt if the frosting is too sweet. Yields about 6 cups of frosting.
Step 6: HOW TO DECORATE THE CAKE: Using a pipping bag filled with vanilla buttercream (about 1 cup) and a 1M pipping tip, pipe rosettes (see below) in random places on the cake. With another pipping bag filled with vanilla buttercream (about 1 cup) and a 8B pipping tip, pipe the design (see above) in random places on the cake. With another pipping bag filled with vanilla buttercream (about 1 cup) and a 102 pipping tip, pipe the design (see above) in random places on the cake. With another pipping bag filled with vanilla buttercream (about 1 cup) and a 4B pipping tip, pipe the design (see above) in the open spots on the cake. If you’d like to take your decorating up a notch add sprinkles and/or gold edible glitter like it did. I suggest doing this right after you finishing piping so they can stick to the frosting.
Step 7: Slice and serve. Cover leftovers tightly and store in the refrigerator for up to 5 days.