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peanut butter brown butter cake
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Brown Butter Peanut Butter Buttercream with Peanut Butter Chocolate Cake

A moist peanut butter chocolate swirl cake topped with a luscious peanut butter buttercream, baked snack cake style.
Prep Time 25 minutes
Cook Time 30 minutes
Servings 10

Ingredients

Brown Butter Peanut Butter Chocolate Swirl Cake

  • ½ cup butter to be browned
  • ⅛ cup canola oil
  • ⅓ cup peanut butter
  • ⅓ cup granulated sugar
  • 2 teaspoons pure vanilla extract
  • ½ teaspoon baking powder
  • ¼ teaspoon salt
  • ¼ teaspoon heaped, baking soda
  • 2 eggs at room temperature
  • 1 cup cake flour
  • ½ cup buttermilk
  • 1 tablespoon cocoa plus ½ tablespoon milk

Peanut Butter Brown Butter Buttercream

  • ½ cup butter for browning
  • ¼ cup butter softened
  • ⅓ cup peanut butter
  • 1 teaspoon pure vanilla extract
  • ½ teaspoon fine sea salt
  • 2 ¼ cup organic powdered sugar
  • 2 tablespoons heavy cream

Instructions

To make the cake

  • Preheat oven to 350 F and grease and line an 8×8 square inch pan with parchment paper.
  • Over medium heat in a saucepan, melt the butter. Continue to cook while the butter sputters, bubbles and foams. Once it goes silent and turns brown, immediately remove from heat and pour into a bowl, scraping up the tiny brown bits from the pan.
  • Into the bowl add the peanut butter, vanilla, sugar and oil and whisk together. This should cool the batter down to be warm to touch. Whisk in the eggs until the batter is smooth. Gently stir in the flour, soda, powder and salt. Add the buttermilk and stir until smooth.
  • Pour half of the batter into the prepared pan and use an offset spatula to push it into the edges.
  • To the other half of the batter add the cocoa and milk, and stir to fully combine. Then pour the now chocolate batter over the peanut butter, and use the offset spatula or a butterknife to swirl the two batters.
  • Bake for 20-30 minutes, until a cake tester turns out clean.

To make the buttercream

  • Brown 1/2 cup butter: Over medium heat in a saucepan, melt the butter. Continue to cook while the butter sputters, bubbles and foams. Once it goes silent and turns brown, immediately remove from heat and pour into a heatproof bowl, scraping up the tiny brown bits from the pan. Let it cool at room temperature and then set it in the fridge for a couple of hours, stirring now and then until it has solidified and is soft and creamy (like the texture of coconut oil). You can speed this up by doing it in the freezer but you’ll need to keep a closer eye on it.
  • In the bowl of a stand mixer, or using a hand mixer, beat the brown butter and softened butter until light and fluffy. Add the peanut butter, vanilla and salt and beat to combine. Add the powdered sugar and beat. The mixture is going to look thick and not-spreadable, don’t worry, we are about to fix it.
  • Add the heavy cream and beat until the buttercream is light and fluffy, as pictured. If it’s still not smooth, add another TB of heavy cream. Once the cake is cool, spread the buttercream over the cake.