Grandma’s Top Secret Peanut Butter Cake Recipe

This peanut butter cake recipe is moist, tender, and ultra decadent! It’s topped with a layer of chocolate crumbles and just a tease of of melted fudge. It can be stacked sky-high in tall, sexy layers or served as a simple sheet cake.

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THIS IS A SPECIAL RECIPE

Some recipes are more sentimental than others, and this one is at the top of my nostalgic list. Whenever there was a church potluck or birthday party, my grandma used to make this cake for me. Well, it might have been for all of us, but it has definitely made the rounds at our parties!

This particular cake was a special request from my oldest for his twelfth birthday! It’s hard to believe he’s growing up so fast, but I’m glad he still loves it when I make him a special cake.

INGREDIENT NOTES

Everything needed for this recipe is something that I usually have on hand. Sugar, butter, eggs, flour… all pretty basic!

The flour can also be swapped with a 1:1 gluten free blend like Bob’s or King Arthur. I’ve used both and the only difference I noticed was that the cake was a little bit more rich instead of light and airy. Let’s be honest, that is kinda a good thing! I’ve never said the words, “oh nooo, this cake texture is too fudgy.” Ya feelin’ me?

The only ingredient that might not be readily available is buttermilk, but don’t worry! I’ve got a trick for that.

HOW TO MAKE A BUTTERMILK SUBSTITUTION

No buttermilk? No problem! To make a buttermilk substitution, simple add a small splash of vinegar to regular milk and let it sit. After a few minutes, the milk will begin to look slightly curdled and taste just like traditional buttermilk. Crisis avoided.

There are a few other swaps that will work, too. Plain sour cream or yogurt can be diluted slightly with water and used in place of buttermilk for baking recipes. Another substitution I have used is adding one tablespoon of fresh lemon juice to a cup of milk and letting it curdle for five minutes. Plenty of options, so don’t get hung up on the buttermilk!

HOW TO MAKE PEANUT BUTTER CAKE

INGREDIENTS FOR THE CAKE

1 CUP BUTTER
½ CUP PEANUT BUTTER (crunchy or creamy)
1 TEASPOON VANILLA EXTRACT
1 CUP WATER
2 CUPS FLOUR
2 CUPS SUGAR
1 TEASPOON BAKING SODA
½ TEASPOON OF SALT

2 EGGS
⅓ CUP BUTTERMILK

How to Make the Cake

1. Prep your pans (important!)
   • For 2-3 layers: Grease the bottoms and sides of 2 or 3 8-inch round cake pans and line the bottoms with parchment paper rounds. These are great for preventing sticking and broken cakes. Then grease the parchment with cooking spray, too.
   • For a sheet cake: Prepare an 11x15 sheet pan by greasing thoroughly. Skip the parchment paper for this one.
   • For a 9X13 cake: Grease the pan thoroughly. Skip the parchment paper.
2. Preheat the oven to 375°F (190°C).
3. Boil wet ingredients
   • In a sauce pan or microwave-safe bowl, combine 1 cup butter + ½ cup peanut butter + 1 cup water. Microwave until the mixture is just boiling, then remove from heat. This takes about 3 minutes in the microwave, but keep an eye on it so that it doesn't boil over.
4. Mix in dry ingredients.
   • In the bowl of your stand mixer, whisk flour, sugar, baking soda, and salt until evenly combined.
5. Combine batter
   • Pour the hot butter/peanut butter mixture over the dry ingredients.
   • Beat on low with a paddle attachment until thick and smooth.
6. Add eggs and buttermilk
   • Add 2 eggs and ⅓ cup buttermilk to the bowl, then beat until just combined.
   • Stir in 1 teaspoon of vanilla.
7. Fill the pans.
   • For layer cakes: divide the batter evenly among the prepared pans.
   • For sheet cakes: Pour batter into prepared pan.
8. Bake - Always start checking early. Cakes are done with the center springs back and a toothpick comes out clean.
   • Three 8-inch layers: bake 18-25 minutes.
   • Two 9-inch layers: bake 25-30 minutes.
   • 11X15 inch sheet pan: bake 22-28 minutes.
   • 9X13 pan: 30-35 minutes.
9. Cool
   • Let cakes cool in pans for 10-15 minutes.
   • Turn out onto a wire rack and cool completely before frosting.

HOW TO MAKE PEANUT BUTTER FROSTING

INGREDIENTS FOR PEANUT BUTTER FROSTING

½ CUP OF PEANUT BUTTER (crunchy OR creamy)
½ CUP BUTTER, ROOM TEMPERATURE
⅓ CUP MILK
1 TEASPOON VANILLA
1 POUND POWDERED SUGAR

Frosting Instructions

1. Beat peanut butter and room temperature butter until light and fluffy.
2. Add powdered sugar and vanilla. Mix until combined.
3. Add milk gradually until frosting reaches desired consistency.
4. Frost the cooled cake.

CAKE DECORATING TIPS

To make this peanut butter cake recipe in a single layer sheet pan, I tend to leave it simple styled with a generous layer of frosting. I frost it while the cake is still slightly warm from the oven and it creates a beautiful and pillowy icing. The warmth from the freshly baked and slightly cooled cake melts the frosting so that it forms a beautiful and smooth glossy layer.

When I made this cake today, I actually made a double batch of frosting. The method I used was the same as working with a standard buttercream frosting. I assembled the layered cake with frosting between the layers and then used a cake decorating spatula to give the sides a smooth and thin layer of frosting. The purpose of this first layer is to create a smooth and even surface that will be a base for the final frosting layer. For this first layer of frosting, I mixed it to a consistency that resembled putty rather than soft and pliable icing.

I popped it in the refrigerator over night and then added the second layer of frosting directly onto the chilled cake. It is so much easier to frost a chilled cake, FYI. The frosting in this layer was mixed with my standard recipe to make it smooth and easier to work with. Once the frosting was smooth, I melted chocolate and used my blender to pulse chocolate chunks into irregular sized pieces and decorated the top of the cake.

PEANUT BUTTER CAKE RECIPE FAQ’S

How long does this cake last? I have kept this cake on the countertop for up to three days without noticing it becoming stale. As long as it is covered with wrap or placed in an airtight container, it should be totally fine.

Can this cake be frozen? Absolutely! The layers of cake can be made up to a month ahead of time and frozen until ready. The entire cake can be stored in the freezer for several months when wrapped well with plastic.

What if I don’t have buttermilk? There are several substitutes for buttermilk in this recipe. I typically mix one cup of whole milk with one tablespoon of vinegar and allow it to sit for five minutes. Then I measure out the amount of buttermilk I need for my recipe, and it is perfect! Other substitutes include plain yogurt diluted with water slightly or sour cream.

If you make this recipe, please leave a comment below! This provides helpful feedback to both me and other readers. For more delicious recipes from scratch and homesteading tips, follow me on instagram @NinnescahHomestead

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