Chocolate Brownie Cake with Peanut Butter Frosting

Recipe By Tessa Arias
  |  
January 8th, 2020
5 from 11 votes
5 from 11 votes

Chocolate Brownie Cake with Peanut Butter Frosting features three layers of fudgy brownie cake with rich peanut butter buttercream topped with chocolate ganache and peanut butter cups. Ultimate decadence!

Yield: 6 servings

Prep Time: 45 minutes

Cook: 25 minutes

Tessa's Recipe Rundown...

Taste: The cake layers are ultra chocolaty and the frosting is ultra peanut buttery. Dessert bliss!
Texture: The brownie cake is super dense, rich, and fudgy but sturdy enough to stack and the buttercream and chocolate topping are the definition of smooth yet rich.
Ease: Not too difficult, just a little time consuming. A great weekend project.
Pros: DELICIOUS.
Cons: None, really.
Would I make this again? Yes yes yes. I want to already.

Happy January! I’m referring to this cake recipe as the Anti New Year’s Resolution cake.

It’s for everyone who can’t stand to hear one more word about resolutions, diets, Keto, and on and on. I dedicate this cake to you 😉

Peanut butter brownie cake on a cake stand topped with dipping chocolate ganache and peanut butter cups with a slice taken out

It truly is all of my dessert dreams come true.

You could definitely use the brownie cake layers in this recipe with any other thick fillings and frostings to get creative with flavors!

But you guys probably already know that I’m obsessed with the chocolate + peanut butter flavor combination. When brownies are involved there… well I’m truly in heaven!

Tips for Chocolate Brownie Cake with Peanut Butter Frosting

How to turn brownies into cake layers

Three 6 inch brownie cake layers

The brownie cake recipe is adapted from the ultra talented Erin of Cloudy Kitchen. She took classic brownies and made them sturdy enough for a layer cake while still remaining rich and fudgy.

The brownie cake layers use a high amount of both melted semisweet chocolate and cocoa powder for an intense chocolate flavor. They also use a combination of butter and oil for the best flavor and moist texture. Tons of eggs help add richness and structure, as does the addition of baking powder (which is not included in my traditional brownie recipes).

Which cake pans are the best?

I love my Fat Daddio anodized aluminum cake pans. They release cakes of all variety easily and don’t dry out the edges. Whatever you do, never bake a cake in a dark colored pan. It’ll likely over bake and be too brown and dry at the edges.

Can I use 8-inch cake pans instead?

This recipe uses three 6-inch cake pans for a beautifully tall cake with the perfect amount of fudgy brownie goodness in every slice.

I haven’t tested this, but can try using two 8-inch cake pans and start checking for doneness at 25 minutes. The cake will obviously be much shorter.

How to Make Creamy Peanut Butter Frosting

Start with butter that’s softened to room temperature and a whole cup of creamy conventional peanut butter. Not the “natural” stuff that doesn’t contain any added added oil. I like to use Skippy.

Why? That added oil helps prevent the peanut butter from separating so it stays homogenous which is definitely what we want for buttercream. If you use a natural peanut butter product that only contains ground peanuts then your buttercream may break and not taste as peanut buttery.

Make sure to sift your powdered sugar before using for the smoothest creamiest buttercream. For even creamier buttercream, try using organic powdered sugar with tapioca starch. It dissolves into the frosting better than the traditional cornstarch so you don’t get any grittiness. For more buttercream tips check out this post.

How to Assemble & Decorate a Layer Cake

Brownie layer cake on a cake stand with a bowl of peanut butter frosting

Place one cake layer on a cake stand or serving plate. Spread with about 1/2 cup of the frosting. Repeat with the remaining two cake layers, leaving the top layer flat side up. This ensures the top of the cake is level with clean edges.

Apply a thin layer of crumb coat icing to the entire surface of the cake, scraping away any excess with an offset spatula or bench scraper to create a spackle-like coating. Be sure not to scrape any crumby icing back into your clean bowl of icing. A cake turntable makes easy work of this. Refrigerate the whole thing until hard, about 15 to 20 minutes.

While the crumb coat is in the fridge make the chocolate drip. You want it to cool until it has thickened but is still pourable. But not so thin that it runs clear down the sides of the cake. It’s a fine balance! The amount of time it takes for the ganache to cool to this consistency will depend on the temperature of your kitchen and the size and shape of your bowl.

Whatever you do, don’t place the ganache drip in the fridge to cool. This will create uneven chunks of cooler ganache next to runnier warmer bits. Test the consistency of the drip by pouring down the side of a glass. If it’s too thick, microwave for 5 to 10 seconds then stir. If it’s too thin, allow to continue to cool.

How to Make the Cake Ahead of Time

The brownie cake layers can be stored in the fridge, wrapped tightly in plastic wrap, for up to 2 days before assembling.

The frosting can also be stored in the fridge, wrapped in plastic wrap, for up to 1 week. Allow to come to room temperature before re-whipping with an electric mixer until smooth and creamy again.

The assembled and frosted cake can be stored, covered, at room temperature for up to 1 day or in the fridge for up to 3 days.

Slice of chocolate brownie cake with peanut butter buttercream

More Cake Recipes You’ll Love

5 from 11 votes

How to make
Chocolate Brownie Cake with Peanut Butter Frosting

Yield: 6 servings
Prep Time: 45 minutes
Cook Time: 25 minutes
Chocolate Brownie Cake with Peanut Butter Frosting features three layers of fudgy brownie cake with rich peanut butter buttercream topped with chocolate ganache and peanut butter cups. Ultimate decadence!

Ingredients

For the brownie cake Layers:

  • 1 stick (113 grams) unsalted butter
  • 8 ounces (227 grams) semisweet baking chocolate, chopped
  • 1 cup (200 grams) granulated sugar
  • 2/3 cup (133 grams) dark brown sugar
  • 3/4 cup (95 grams) all-purpose flour
  • 1 cup (85 grams) unsweetened natural cocoa powder
  • 3/4 teaspoon baking powder
  • 1/2 teaspoon salt
  • 5 large eggs, at room temperature
  • 1/2 cup fresh vegetable oil
  • 1 teaspoon vanilla extract

For the peanut butter frosting:

  • 2 sticks (227 grams) unsalted butter, at room temperature
  • 1 cup (270 grams) creamy conventional peanut butter
  • 1 teaspoon vanilla extract
  • 1/8 teaspoon fine salt
  • 2 1/2 cups (313 grams) powdered sugar, sifted

For the chocolate drip:

  • 4 ounces (113 grams) semisweet or bittersweet chocolate, finely chopped
  • 1/2 cup heavy cream
  • Chopped peanut butter cups, optional

Directions

Make the cake layers:

  1. Preheat the oven to 350°F. Grease and line three 6-inch cake pans with parchment paper.
  2. In a heatsafe bowl, combine the butter and chocolate and microwave for 45 seconds. Stir and continue to heat in 30-second bursts, stirring between bursts, until melted and smooth. Whisk in the sugars until combined. Let cool.
  3. In a small bowl, whisk together the flour, cocoa powder, baking powder, and salt.
  4. To the cooled chocolate mixture whisk in the eggs, one at a time, Whisk vigorously for 30 seconds until very well combined. Add in the oil and vanilla and whisk until combined. Add the dry ingredients and gently fold to combine.
  5. Divide the batter between the three cake pans, and tap on the counter to prevent air bubbles.
  6. Bake for 25 to 30 minutes, or until the tops are dry and a cake tester inserted in the middle comes out with a few crumbs attached. Be sure not to overbake, the cakes will continue to cook after being removed from the oven.
  7. Cool in pans for 10 minutes, then turn out onto a wire rack and allow to cool completely. At this point the brownie cake layers can be stored in the fridge, wrapped tightly in plastic wrap, for up to 2 days before assembling.

Make the frosting:

  1. In the bowl of an electric mixer fitted with the paddle attachment, beat the butter and peanut butter on medium-high speed until light and fluffy, scraping down the sides and bottom of the bowl as needed. Add the vanilla, salt, and powdered sugar and continue beating until the frosting is smooth and fluffy, about another 3 minutes.

Assemble the cake:

  1. Place one cake layer on a cake stand or serving plate. Spread with about 1/2 cup of the frosting. Repeat with the remaining two cake layers, leaving the top layer flat side up.
  2. Apply a thin layer of crumb coat icing to the entire surface of the cake, scraping away any excess with an offset spatula or bench scraper to create a spackle-like coating. Refrigerate until hard, about 15 to 20 minutes.
  3. Spread the remaining frosting in an even layer all over the cake. Refrigerate while you make the chocolate drip.

Make chocolate drip:

  1. Place the chopped chocolate in a heatproof bowl. Bring the heavy cream to a simmer then immediately remove from heat and pour over chocolate. You can also do this in the microwave. Cover for a few minutes then stir until smooth.
  2. Allow to cool until it has thickened but is still pourable, about 10 minutes. Don’t place ganache in the fridge to cool. Test the consistency of the drip by pouring down the side of a glass. If it’s too thick, microwave for 5 to 10 seconds. If it’s too thin, allow to continue to cool. Spread the drip all over the top of the cake and allow it to drip down the sides.

  3. Allow to set slightly before garnishing with the peanut butter cups, if using.

  4. The cake can be stored, covered, at room temperature for up to 1 day or in the fridge for up to 3 days.

Recipe Notes

Brownie cake adapted from Cloudy Kitchen.
Course: Dessert
Cuisine: American
Keyword: ganache, peanut butter cups

Photos by Ashley McLaughlin.

About Tessa...

I share trusted baking recipes your friends will LOVE alongside insights into the science of sweets. I'm a professionally trained chef, cookbook author, and cookie queen. I love to write about all things sweet, carb-y, and homemade. I live in Phoenix, Arizona (hence the blog name!)

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