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Chocolate Peanut Butter Cake Recipe

yield: 1 3-layer, 8-inch cake
5 from 2 votes

Special Equipment

  • Special Equipment: a food processor


For the Peanut Butter Brown Sugar Cake

  • 2 ¼ cups (9 ounces or 255 grams) cake flour
  • 2 cups tightly packed (15 ounces or 425 grams) light OR dark brown sugar
  • 1 ½ teaspoons baking powder
  • 1 ½ teaspoons baking soda
  • 1 ½ teaspoons kosher salt
  • 1 cup (9.5 ounces or 269 grams) unsweetened creamy natural peanut butter
  • 1 cup (8 ounces or 227 grams) buttermilk
  • ¾ cup (6 ounces or 170 grams) water
  • ½ cup (4 ounces or 113 grams) canola oil
  • 2 large eggs
  • 2 teaspoons pure vanilla extract

For the Chocolate Fudge Frosting

  • 6 ounces (170 grams) unsweetened chocolate from a high-quality chocolate bar, hand broken into pieces
  • 4 ½ cups (18 ounces or 510 grams) confectioners’ sugar, sifted
  • 1 ½ cups (12 ounces or 340 grams) unsalted butter, at room temperature
  • 6 tablespoons (3 ounces or 85 grams) whole milk
  • 1 tablespoon pure vanilla extract
  • ¼ teaspoon kosher salt


Day 1: Make the Peanut Butter Brown Sugar Cake

  • Position a rack in the center of the oven and preheat the oven to 350°F. Generously spray three 8-inch cake pans with cooking spray and line the bottom(s) with parchment paper (cut to fit). Spray the parchment, too.
  • In a medium bowl, whisk together the flour, brown sugar, baking powder, baking soda, and salt.
  • In the bowl of a stand mixer fitted with the whisk attachment, combine the peanut butter, buttermilk, water, oil, eggs, and almond extract. Whisk on low until the mixture is smooth and caramel in color, about 1 minute. Gradually add the dry ingredients, using a rubber spatula to scrape down the bottom and sides of the bowl as necessary. Take extra care here—a small amount of peanut butter always sticks to the bottom. Whisk on low until just combined.
  • Pour the batter into the prepared pans. Note that this recipe makes around 54 ounces (1531 grams) of batter; pour 18 ounces (510 grams) into each cake pan and bake for 35 to 40 minutes. When done, the top of the cakes should bounce back when gently pressed and a skewer inserted into the center of each cake should come out with a few crumbs attached. Cool completely in the pans on a wire rack.
  • Once cool, turn each cake out of its pan over a sheet of plastic wrap. Peel off the parchment paper and discard. Wrap each cake in the plastic wrap, ensuring that very inch of its surface area is covered tightly. Freeze overnight.

Day 2: Make the Fudge Frosting and Assemble the Cake

  • Remove the cakes from the freezer and set aside at room temperature while you make the frosting.
  • Make the frosting: In a food processor, pulse the chocolate for a few seconds at a time until chopped into 1- to 2-inch pieces. Transfer the chocolate to the top of a double boiler or to a heatproof bowl set over a medium, heavy-bottomed saucepan filled with a few inches of simmering water (be sure the bottom of the bowl does not touch the water). Cook over medium heat, using a heatproof rubber spatula to stir the mixture and scrape the sides of the bowl occasionally, until the chocolate has melted, about 10 minutes. Set the top of the double boiler or the bowl on a wire rack and let the chocolate cool while you prep the other ingredients.
  • In the food processor, combine the confectioners’ sugar, butter, milk, vanilla, and salt. Pour in the melted chocolate and pulse briefly to combine, then process until the frosting is creamy, smooth, and light brown in color, about 5 minutes. Scrape down the bottom and sides of the bowl with a rubber spatula, then process for an additional 30 seconds.
  • Unwrap one of the cakes and place on a serving plate or cake board. Scoop out ¾ cup of the frosting and drop it right in the middle of the top of the cake. Use an offset spatula to spread it evenly all over the top, just like you would spread butter on toast. There's no need to frost the sides of the cake just yet, so avoid frosting the sides—but also, don't worry if some frosting accidentally ends up there, too. We'll fix it later.
  • Place your second cake layer on top of the first, adjusting it if it’s crooked—the layers should be stacked evenly on top of each other. Scoop another ¾ cup of the frosting and repeat the previous step on this layer. Finally, nestle the last layer on top of this frosting.
  • Use an offset spatula to spread a thick, even layer of frosting all over the top and sides of the cake, adding a little bit of frosting at a time. Then use the spatula to make large, random sweeping motions across the frosting on the top and sides of the cake; the sweeping motions will create the swirls. Don’t overthink it! For this method, a little work goes a long way. I promise it’ll be beautiful no matter what you do.