Description

This Chocolate Brownie Cake with Peanut Butter Frosting is the ultimate dessert mashup—dense, fudgy brownie meets soft, sliceable cake, all topped with a rich, creamy peanut butter frosting. It’s easy to make, intensely chocolatey, and perfectly balanced with the sweet-salty depth of peanut butter. Whether you’re baking for a party, a birthday, or just a chocolate craving, this cake is sure to impress and satisfy. Make it from scratch for full control over flavor and texture, or use your favorite boxed brownie mix for a shortcut. Either way, this dessert delivers big flavor with every bite.

Ingredients

Scale

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

Instructions

Preheat the oven to 350°F. Grease and line three 6-inch cake pans with parchment paper.
In a heat-safe 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.
In a small bowl, whisk together the flour, cocoa powder, baking powder, and salt.
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.
Divide the batter between the three cake pans, and tap on the counter to prevent air bubbles.
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.
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.

Notes

Type of Peanut Butter: For best frosting texture, use creamy commercial peanut butter like Jif or Skippy. Natural peanut butter may separate and affect the consistency.
Make Ahead: You can bake the cake a day in advance and store it tightly wrapped at room temperature. Frosting can be made ahead and stored in the fridge—bring to room temp before spreading.
Storage: Store leftovers in an airtight container at room temperature for up to 3 days, or in the fridge for up to 5 days.
Freezing Instructions: Freeze whole or sliced, tightly wrapped, for up to 2 months. Thaw in the refrigerator overnight and bring to room temperature before serving.
Optional Add-ins: Mix chocolate chips, espresso powder, or swirl in caramel for a twist.
Dietary Swaps: For gluten-free, use a 1:1 gluten-free flour blend. For dairy-free, sub plant-based butter and milk in both the cake and frosting.
Serving Idea: Warm slices slightly and top with a scoop of vanilla ice cream or a drizzle of melted chocolate for an extra decadent touch.