Grandma’s Top Secret Peanut Butter Cake Recipe

This peanut butter cake 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

PROCESS FOR BAKING THE CAKE

1. In a glass bowl, combine butter, peanut butter and water. Microwave until it comes to a rolling boil.
2. In a stand mixer, whisk to combine flour, sugar, baking soda and salt.
3. Pour the wet ingredients over the dry ingredients and beat with a paddle attachment on a slow speed until well incorporated. It will be thick and have several air bubbles.
4. Add the eggs and buttermilk and continue beating until just combined. Avoid over mixing at this step!
5. Pour into a greased sheet cake pan and bake at 375° for 20 to 25 minutes. For a layered cake like mine, use two 8 inch cake pans that have been greased and lightly floured. Bake at 375 for about 30 minutes.

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

PROCESS FOR MAKING THE FROSTING

1. In a stand mixer with whisk attachment, beat the butter and peanut butter for two minutes until light and fluffy. Add the powdered sugar and vanilla and whisk it until the frosting looks like coarse sand. This takes about five minutes.
2. Gradually add the milk until the consistency is as thick or thin as you like.

CHEF’S NOTE: For this layered cake, I had to use a double batch of frosting. I decorated it with chocolate chips that I pulsed in the blender until they were crumbled and then poured a puddle of melted chocolate chips on top. I sprinkled a pinch of sea salt flakes on top to give it a little hint of sparkle.

CAKE DECORATING TIPS

For a peanut butter cake made 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.

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