Last month, Ian celebrated his THIRTIETH birthday. To celebrate, I baked him a 4-tiered, peanut butter cup cake. A lot of recipes online simply did chocolate cake with a peanut butter frosting. But I wanted the cake itself to have chocolate & peanut butter combo. The result? Peanut butter goodness.
Ultimate Peanut Butter Cup Cake
Chocolate Peanut Butter Cake
- 2 cups granulated sugar
- 1 3/4 cup all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 1/2 tsp baking powder
- 1 1/2 tsp baking soda
- 1 tsp salt
- 2 large eggs
- 1 cup buttermilk
- 1/2 cup sour cream
- 1/2 cup creamy peanut butter
- 2 Tb vegetable oil
- 1 tsp vanilla extract
- 1 cup boiling water
Peanut Butter Buttercream
- 1 1/2 cup unsalted butter, room temperature
- 1 1/2 cup creamy peanut butter
- 5 cups powdered sugar
- 1 tsp salt
- 2 tsp vanilla extract
- 1/4 cup milk
- 1 cup semi-sweet chocolate chips
- 1/2 cup heavy cream
- 6 Reese’s peanut butter cups, coarsely chopped
- Preheat oven to 350°F. Grease two 6-inch deep cake pans with unsalted butter. Sprinkle with 1 tablespoon of flour. Gently rotate and tap the pan, until the entire pan is lightly coated with flour. Tap out the excess.
- In a large mixing bowl, stir together flour, sugar, cocoa powder, baking powder, baking soda, and salt. Add eggs, buttercream, sour cream, peanut butter, oil, and vanilla extract. Beat on medium speed for 2-3 minutes. Gently stir in boiling water until combined. Pour cake into prepared pans and bake the cakes for 30-35 minutes.
- Remove cakes and place on wire racks until completely cool. Turn cakes out. Slice each cake in the middle horizontally so you have 4 layers in total.
- While the cakes are baking, make the buttercream by whipping unsalted butter on high speed until light and fluffy. Add the peanut butter and continue to whip until creamy. Slowly add powdered sugar, 1/2 cup at a time, whipping on low speed until each addition is incorporated. Add salt, vanilla extract and whip until fluffy. Slowly add milk until desired consistency.
- Make the ganache – melt the chocolate chips and heavy cream in a double boiler, stirring occasionally until glossy. Set aside to let cool slightly. (You could also make the ganache in a microwave by microwaving in 30-second intervals)
- Assemble the cake – put one cake layer on a cake board. Add some buttercream and smooth out. Repeat with additional layers until the final layer of cake is adhered. Spread the remaining buttercream on top and sides of cake, smooth out the cake as needed. Spoon cooled ganache over the top of the cake, and use a spoon to encourage the ganache to drip down the sides. Top with chopped peanut butter cups.