Peanut Butter Cup Banana Cake

Course: Dessert
Cuisine: American
Keyword: banana, banana cake, homemade cake, peanut butter cup
Dessert Type: Cake
Prep Time: 10 minutes
Cook Time: 20 minutes
Total Time: 20 minutes
Servings: 16
Calories: 756kcal
Author: Elizabeth LaBau
This Peanut Butter Cup Banana Cake combines 3 of my favorite things: peanut butter, chocolate, and banana. This was a massive cake that easily served about a dozen people at the party we took it to, with lots of leftovers to spare. It’s rich, so smaller pieces are very satisfying.
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For the Banana Cake:

  • 10 1/2 oz sugar (1 1/2 cups)
  • 8 oz bananas mashed, ripe (1 cup)
  • 4 fl oz vegetable oil (1/2 cup)
  • 2 large eggs at room temperature
  • 2 fl oz buttermilk (1/4 cup)
  • 1 teaspoon vanilla extract
  • 9 oz all-purpose flour (2 cups)
  • 1 teaspoon baking soda
  • 1 teaspoon ground cinnamon
  • 1/2 teaspoon salt

For the Milk Chocolate Frosting:

  • 12 oz unsalted butter at room temperature (1 1/2 cups)
  • 2 oz powdered sugar sifted (1/2 cup)
  • 1 1/2 oz dark cocoa powder sifted (1/2 cup)
  • 1/3 cup hot water
  • 2 oz sour cream (1/4 cup)
  • 2 tsp pure vanilla extract
  • 1/8 teaspoon salt
  • 10 ounces milk chocolate chopped, melted and cooled slightly
  • 5 ounces dark chocolate chopped, melted and cooled slightly

For the Peanut Butter Frosting:

  • 4 oz powdered sugar (1 cup)
  • 9 1/2 oz peanut butter (1 cup)
  • 2 1/2 oz unsalted butter at room temperature (5 tbsp)
  • 1 tsp vanilla extract
  • 1/4 tsp salt
  • 1/4 cup heavy or whipping cream (2 oz)

To Assemble:

  • 3-4 cups assorted sizes peanut butter cups


To Make the Banana Cake:

  • Preheat the oven to 350°F. Spray four 8-inch cake pans with nonstick cooking spray, line the bottoms with parchment rounds, then lightly spray the parchment. (You can use 2 or 3 9-inch cake pans if you want fewer, wider layers.)
  • Combine the sugar, banana, oil, eggs, buttermilk, and vanilla in the bowl of a large stand mixer fitted with a paddle attachment. Beat everything together on medium-low speed until well blended.
  • In a separate bowl, sift together all of the dry ingredients. Add the drys to the banana mixture and beat well. Finish by scraping the bottom and sides of the bowl with a rubber spatula to make sure there are no dry patches. Divide the batter equally between the four pans.
  • Bake the cakes until the tops spring back lightly when pressed and a toothpick inserted into the center comes out clean, about 20 minutes. Cool the cakes in the pans for 15 minutes, then turn out onto wire racks and cool completely. Cakes can be made in advance, wrapped in plastic wrap, and frozen until ready to use. I find it's a bit easier to work with cold banana cake (it's less delicate) so even if you're assembling these the same day you bake them, try to put them in the freezer for at least 20-30 minutes to firm them up a bit before assembling the cake.

To Make the Milk Chocolate Frosting:

  • In the bowl of stand mixer fitted with a paddle attachment, beat the butter on medium speed until pale and fluffy, about 6 minutes. Reduce to speed to low, and add the powdered sugar, cocoa powder, water, sour cream, vanilla, and salt and beat until incorporated, about 1 minute. Increase the speed to medium and beat for 2 more minutes.
  • Add the melted chocolates and beat on medium speed until smooth, about 1 minute. Use immediately for the best texture.

To Make the Peanut Butter Frosting:

  • Combine the powdered sugar, peanut butter, butter, vanilla, and salt in the bowl of a large stand mixer fitted with a paddle attachment. Mix them together on medium-low speed until they're combined and the dry sugar disappears, scraping down the bowl with a rubber spatula as you work. Add 2 tablespoons of cream and beat on medium-high speed until the mixture is light, fluffy and smooth. Add up to 2 more tablespoons of cream if necessary, to get a light and smooth texture. The peanut butter frosting can be made in advance and kept in an airtight container in the refrigerator for several days. Let it come to room temperature before spreading it if you make it in advance.

To Assemble:

  • Place one cake on a cardboard cake round, and top it with about half of the peanut butter frosting. Use an offset spatula or knife to spread the frosting evenly to the edge of the cake. Press a second cake round on top, and this time top it a generous cup of chocolate frosting.
  • Repeat again, using the remaining peanut butter frosting as the third frosting layer. After all the cake layers are added, spread a very thin layer of chocolate frosting over the top and sides of the cake. Refrigerate the cake for 30 minutes to firm it up and make it easier to decorate.
  • Once the cake has firmed up, spread the remaining chocolate frosting over the top and sides of the cake. Decorate around the edges of the top and bottom with peanut butter cups or any other decorations you'd like. Store the cake in the refrigerator for up to 7 days, but for the best taste and texture, serve it at room temperature.


The banana cake is adapted from Bon Appetit, and the chocolate frosting is adapted from


Calories: 756kcal | Carbohydrates: 69g | Protein: 9g | Fat: 52g | Saturated Fat: 29g | Cholesterol: 83mg | Sodium: 328mg | Potassium: 386mg | Fiber: 5g | Sugar: 48g | Vitamin A: 770IU | Vitamin C: 1.2mg | Calcium: 52mg | Iron: 3.2mg