• Lauren Humphreys

Chocolate Peanut Butter Cake

Birthdays always call for extravagant desserts, but especially birthdays during quarantine! To celebrate Rob’s 35th birthday this past Friday, I made him this decadent chocolate cake with peanut butter mousse filling and covered it with fudge frosting. It’s like a Reese’s peanut butter cup but in cake form! Rob’s birthday was obviously low-key but enjoyable nonetheless!

Here’s a quick run-down of the components of the cake:

Chocolate Cake

The cake itself is a dark, moist, and beautiful chocolate cake! Just look at it! It is reminiscent of a devil’s food cake and comes together quickly since it is made with oil. You do not have to let butter soften or cream it. This cake recipe is one we have been making in our family for over a decade and it never fails us. We first found it in a Midwest Living magazine and it’s called “Café Latte’s Turtle Cake.” Here is a link to the recipe if you’re curious:


I prepared this cake in three 8-inch cake pans. The original recipe calls for three 9-inch cake pans but the cake layers end up ultra thin. I only recommend using the 8-inch cake pans for my recipe. You will notice that it contains 1 cup of hot coffee in the cake. You do not taste the coffee in the cake itself but it brings out the cocoa flavor. Rob hates coffee, and he never would have guessed there was coffee in it.

Peanut Butter Mousse

The peanut butter mousse is not a true mousse, but it is perfect in this cake! It had to be sturdy enough to hold up inside of this cake without being too firm. It tastes very similar to the filling of a peanut butter pie. It is so luscious, rich, and full of peanut butter flavor! To be honest, I could eat it plain by the spoonful. The color contrast with the dark cake layers also looks beautiful and elegant.

Fudge Frosting

I came across this gem of a recipe in a Better Homes and Garden cookbook. I made some minor revisions, but it truly does taste like fudge. It is also way easier to make than other buttercreams. Sometimes buttercream frostings taste too much like butter, which is not the most pleasant on an already rich cake.

This frosting will seem a bit thin when you first prepare it. As it cools down, it will thicken up. I recommend refrigerating it until you are ready to use it. It will become quite solid, but it rewhips up into a pillowly and pipable frosting. I used my KitchenAid mixer on high speed and it truly is a magical frosting as far as I’m concerned. It spreads and pipes easily once whipped. The taste is incredible too!

The frosting makes just enough for this cake, so keep that in mind when frosting your cake. Try not to use too much frosting when piping your ring barrier for the filling, or you may run out when frosting the tops and sides. This frosting would also work well on a 9x13 inch cake too! It comes together so nicely.

I hope you love this recipe as much as we do! The recipe is broken out by each of the three components, with final instructions at the bottom for assembly. I also included many photos! If you make it, please tag me on Facebook or on Instagram {@mitch8blog]!

Chocolate Cake

1 egg, lightly beaten

1 cup buttermilk or sour milk* (see note below)

2/3 cup vegetable oil

2 cups all-purpose flour

1 ¾ cups sugar

½ cup unsweetened cocoa powder

1 Tbsp baking soda

1 tsp salt

1 cup freshly brewed hot coffee

Additional unsweetened cocoa powder for dusting the pans

Preheat oven to 350° F. Prepare three 8-inch cake pans** by lining the bottoms with a circle of parchment paper for easy removal once baked. Secure in place by greasing the outer edges with some shortening. Lightly grease the parchment paper and dust the pans with cocoa powder.

In a large bowl, sift together the flour, sugar, cocoa powder, baking soda, and salt. In a medium bowl, whisk together egg, buttermilk and oil. Gradually add buttermilk mixture to flour mixture, beating with an electric mixer until combined. Gradually beat in hot coffee. The batter will be very thin. Do not be alarmed. Pour batter into the prepared pans.

Bake for about 20-25 minutes or until a wooden toothpick inserted in the center comes out clean. Cool cakes on a wire racks for 10 minutes. Loosen sides and remove cakes from pans. Peel off the parchment paper circles and let cool completely.


*If you don't have buttermilk, substitute sour milk in the same amount. To make 1 cup of sour milk, place 1 Tbsp of lemon juice or vinegar in a glass measuring cup. Add enough milk to make 1 cup total liquid and stir. Let mixture stand for 5 minutes before using.

**If you only have two 8-inch cake pans, refrigerate 1/3 of the batter while you bake the other two layers. Clean and prepare one of the pans as directed, and bake remaining batter.

Peanut Butter Mousse Filling

½ cup heavy cream

4 oz (1/2 of an 8 oz package) cream cheese, softened

½ cup creamy peanut butter

½ tsp vanilla

1 cup powdered sugar

Using an electric mixer, beat the heavy cream until soft peaks form. Cover and set aside in the refrigerator while preparing the remaining ingredients.

In a separate bowl, combine the cream cheese and peanut butter. Beat for several minutes with an electric mixer until it is completely smooth and fluffy. Scrape sides occasionally to ensure no lumps. Once smooth, add the vanilla and powdered sugar. Continue mixing until smooth and airy.

Lastly, add the whipped cream and mix until incorporated. The mixture should be creamy and light. Refrigerate until ready to assemble cakes.

Fudge Frosting

4 ½ cups powdered sugar

½ cup unsweetened cocoa powder

½ cup (1 stick) butter, softened and cut into slices

1/3 cup boiling water

1 tsp vanilla

Pinch of salt, optional

Sift together the powdered sugar and cocoa. Add the butter, boiling water, vanilla, and salt. Beat with an electric mixer on low speed until combined. Once thoroughly mixed, mix on high speed for about 2-3 minutes. Let cool for about 30 minutes at room temperature (or in the refrigerator to speed up the cooling). If refrigerated, the frosting will become very firm and set.

When ready to use, rewhip with an electric mixer for another couple minutes until light and fluffy. It will be a nice and thick consistency for spreading and piping. Use immediately.

To Assemble Cake

Once cakes are completely cooled, you may being assembly. Level the tops of the cakes, if necessary, so they are completely flat and even. Using a #2A round piping tip, pipe a ring of fudge frosting around the top edge of the cake to hold the peanut butter mousse in place. Add half of the peanut butter mousse and spread evenly. Top with the second cake layer and repeat the previous steps with the ring of frosting and peanut butter filling. Top with the third cake layer and apply a very thin crumb coat around the exterior of the cake. Place in the freezer for about 15 minutes to allow the crumb coat to set.

Once the crumb coat is set, finish frosting the cake with the fudge frosting based on your decorating preferences. You may smooth out the edges with an offset spatula or metal dough scraper. If desired, use a #2D drop flower piping tip to create swirls on the top of the cake. Top with sprinkles for extra color!

Store leftover cake tightly wrapped or in an airtight container in the refrigerator. Let sit for at least 30 minutes at room temperature before serving to allow the fudge frosting to soften.

For the Chocolate Cakes

Cut parchment paper circles to fit the bottoms of the pans

Grease the outer edge to secure the parchment paper


Lightly grease the parchment paper and dust with cocoa powder

Sift together dry ingredients

Stir to ensure it is evenly mixed

Whisk the egg, oil, and buttermilk

Mix until combined. Once it looks like this, you will add the coffee.

Bake and let cool

For the Peanut Butter Mousse

Whip the heavy whipping cream first and set aside

Peanut butter

Use softened cream cheese (1/2 of a 8 oz package)

Mix the peanut butter and cream cheese until light and smooth

Once you add the remaining ingredients, it will look like this

And done!

For the Frosting

Use softened, cut-up butter

Combine and sift the powdered sugar and cocoa powder

Add the remaining ingredients and mix well. It will appear dark and thin.

Keep whipping and let cool

Once cooled completely and thickened, rewhip until light, airy, and fluffy.

For Cake Assembly

Pipe a ring of fudge frosting around the edge of the cake as shown

Add peanut butter filling. Repeat this process for the second layer

Pipe additional decorations on top and add sprinkles

Top view

Inside view

Cake slice view

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