Peanut Butter Chocolate Bumpy Cake

by Erin

The famous Michigan chocolate bumpy cake gets a buckeye twist with stripes of peanut butter buttercream piped over a rich chocolate cake topped with fudge frosting.

Peanut Butter Chocolate Bumpy Cake.

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Today Ohio State plays that cheating team from up North. A team that somehow is playing the victim of their own crimes, using it to band together. As such I am nervous about going into the big house for the game. Even if the game were at home I would still be on edge, just a smidge less. There are always fights but tension is running extra high this year.

In honor of these bumpy times I decided to take a famous Michigan cake, chocolate bumpy cake, and make a buckeye version. They stole our signs so I am stealing their cake!

Slice of Peanut Butter Chocolate Bumpy Cake on a plate.

Have you heard of chocolate bumpy cake before? It’s a chocolate sheet cake that was born out of an accident of Fred Sanders Schmidt having too little frosting and deciding to just pipe lines of buttercream before pouring chocolate fudge icing on top. Long story short, it became the famous Sanders Confectionery Chocolate Bumpy Cake.

But what if you changed the buttercream to peanut butter buttercream? After all, peanut butter buttercream is basically the same as the filling of Buckeye Candies just slightly different proportions. And I’m pretty sure peanut butter > regular buttercream any day. And just like that the Peanut Butter Chocolate Bumpy Cake was born in honor of The Game: Ohio State vs Michigan.

Chocolate Bumpy Cake with Peanut Butter Buttercream.

Peanut Butter Chocolate Bumpy Cake.


Yield: 24 Servings Prep Time: Cooking Time:
Nutrition facts: 200 calories 20 grams fat



  • 1/2 cup (43g) Dutch-process cocoa
  • 1/2 cup (113g) brewed coffee or water, hot
  • 1/2 cup (99g) vegetable oil
  • 1 cup (227g) buttermilk, room temperature
  • 1 1/2 tsp baking soda
  • 1/2 tsp salt
  • 2 tsp vanilla extract
  • 2 large eggs, room temperature
  • 1-3/4 cups (347g) granulated sugar
  • 2 cups (240g) all-purpose flour


  • 8 Tbsp (1/2 cup/113g) unsalted butter, at room temperature
  • 1/2 cup (125g) creamy peanut butter
  • 1/8 tsp salt
  • 2 cups (227g) powdered sugar, sifted
  • 1 tsp vanilla extract
  • 1-2 Tbsp (14-28g) milk, as needed


  • 1/2 cup (113g) buttermilk
  • 2 Tbsp (39g) dark corn syrup
  • 1 cup (226g) unsalted butter, divided
  • 1/2 cup (43g) Dutch-process cocoa
  • 1/4 tsp salt
  • 4 cups (454g) powdered sugar, sifted
  • 1 tsp vanilla extract


  1. Preheat the oven to 350°F. Grease a 9x13-inch pan; set aside.
  2. For the cake: In a large mixing bowl, whisk together the cocoa and hot coffee until smooth. Whisk in the oil and buttermilk until combined.
  3. Using a hand mixer, add the baking soda and salt and beat for 30 seconds. Then add the vanilla and eggs, mixing just until smooth. Add the sugar and flour and beat for 2 minutes at medium speed.
  4. Pour into the prepared pan. Bake for 33-35 minutes, or until the top springs back when lightly pressed and the edges just begin to pull away from the pan.
  5. Remove from the oven and cool for 30 minutes on a wire rack, then place in the freezer for 30 minutes.
  6. For the peanut butter buttercream: In a medium mixing bowl, beat the butter, peanut butter, and salt together until lighter in color, about 2 minutes. Add the powdered sugar and vanilla and beat until the frosting is fluffy, then add 1 tablespoon of milk if needed for a smooth consistency.
  7. Transfer the frosting to a piping bag with a 1/2-inch round tip. If soft, chill in the refrigerator for 5-10 minutes.
  8. Pipe the buttercream across the cake's shorter side (9") in 1/2"-diameter strips, one inch apart. Return to the freezer while you prepare the frosting.
  9. For the fudge frosting: In a medium saucepan with a heavy bottom, combine the buttermilk, dark corn syrup, 1/2 cup of butter, cocoa, and salt over medium heat.
  10. Bring to a boil and cook for 2-3 minutes, until the bubbles make a snapping sound as they pop (or until the mixture reaches 235°F). Immediately stir in the remaining butter, one tablespoon at a time, until incorporated.
  11. Turn the heat to low and whisk in the powdered sugar until it melts and the frosting is smooth and glossy. Remove from the heat, stir in the vanilla.
  12. Remove the cake from the freezer. Immediately drizzle the frosting over the surface of the cake, covering all the buttercream and tilting to fill in any gaps. If needed, gently rewarm the icing and pour again.
  13. Refrigerate cake until ready to serve, slicing into 24 pieces. Store any leftovers tightly covered in the refrigerator for up to a week.
Did You Make This Recipe?
I want to see! Tag me on Instagram at @TheSpiffyCookie and hashtag it #TheSpiffyCookie.

Source: Adapted from King Arthur and The Kitchn.

Did you make this recipe? I want to see! Tag @THESPIFFYCOOKIE on Instagram and hashtag it #THESPIFFYCOOKIE

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