Go Back

The Best Peanut Butter Banana Cake with Peanut Butter Buttercream

Print Recipe
Tender Peanut Butter Banana Cake layers with soft and creamy peanut butter buttercream.
Servings 12 slices
Author Mandy Merriman - Baking with Blondie

Ingredients

Peanut Butter Banana Buttercream

  • 2-3 Ripe Bananas (3 small or 2 medium)
  • 1/4 cup Skippy Creamy Peanut Butter
  • 3/4 cup Buttermilk room temperature
  • 2/3 cup Sour Cream room temperature
  • 4 large egg whites room temperature
  • 1/3 cup vegetable oil
  • 1 Tablespoon vanilla
  • 1 box white cake mix

Peanut Butter Buttercream

  • 1 1/2 cup unsalted butter left out at room temperature for 10 minutes
  • 1 pinch salt
  • 1 Tablespoon vanilla
  • 1/2 cup Skippy creamy peanut butter
  • 1/2 cup heavy cream
  • 7-8 cups powdered sugar

Garnish

  • melted peanut butter for drizzling
  • sliced banana slices

Instructions

For the Peanut Butter Banana Cake Layers

  • Preheat the oven to 325 degrees, convection bake, and prep two cake rounds with baking spray, parchment rounds, or shortening + flour to prevent non-sticking. Set aside.
  • In a large bowl, hand-whisk together all the ingredients and then sift in the cake mix. Gently fold in the cake mix (don't overmix!) and then split the cake batter between the prepared cake pans. Bake for 32-25 minutes until the center is baked through. Don't overbake. Let cool completely, wrap in plastic wrap, then place into the freezer flat for easier stacking later.

For the Peanut Butter Buttercream

  • In a stand mixer fitted with the paddle attachment, whip up the butter until it's light and fluffy. Add in the salt, vanilla, peanut butter, and heavy cream and whip up again. Scrape down the sides, then slowly add in the powdered sugar on low speed until the powdered sugar has been fully incorporated. If too thick, add in a tablespoon or two more of heavy cream if needed. Flip the mixer on the highest speed and whip up for 2 minutes until the buttercream is light and fluffy. Beat down with a wooden spoon to remove any air bubbles.

Assemby

  • Add on a small bit of buttercream on the cake table or cardboard cake round. Place down the first cake layer. Spread on an even layer of buttercream, then add on the second cake layer. Press down firmly, then crumb coat the cake. Place into the freezer for 5 minutes to set the crumb coat, then add on the final layer of buttercream. I used a scallop cake scraper for the decorative sides on this one. Spread on some of the melted peanut butter if using, then hand place on the sliced bananas right before serving. Enjoy!