Chocolate Peanut Butter Birthday Cake

Chocolate Peanut Butter Birthday Cake

Three chocolate cake layers hold two bands of peanut butter buttercream, while chocolate frosting covers the top and sides. A piped peanut butter border and chopped peanut butter cups finish the cake. Remove a serving wedge to show the dark crumb and pale filling.

Use three matching 8-inch pans so the layers bake at a similar rate, and check the centers rather than relying on the clock alone. Let the cakes cool completely before stacking; warm layers can soften the filling and make the cake shift. Allow about 3 hours for baking, cooling, and assembly.

Ingredients

Chocolate Cake

• 2 cups all-purpose flour (250g)
• 2 cups granulated sugar (400g)
• ¾ cup unsweetened cocoa powder (75g)
• 2 teaspoons baking powder
• 1½ teaspoons baking soda
• 1 teaspoon fine salt
• 2 large eggs
• 1 cup buttermilk (245g)
• ½ cup neutral oil (110g)
• 2 teaspoons vanilla extract
• 1 cup hot brewed coffee (240g), or hot water

Peanut Butter Frosting

• 1 cup unsalted butter, softened (225g)
• 1 cup conventional creamy, no-stir peanut butter (260g)
• 4 cups powdered sugar (480g)
• 3 to 5 tablespoons heavy cream or milk

Chocolate Frosting and Topping

• 1 cup unsalted butter, softened (225g)
• ¾ cup unsweetened cocoa powder (75g)
• 4 cups powdered sugar (480g)
• 4 to 6 tablespoons heavy cream or milk
• About 1 cup chopped chocolate peanut butter cups (170g)

How to Make Chocolate Peanut Butter Birthday Cake

1. Prepare the pans: Preheat the oven fully to 350°F (175°C). Grease three matching 8-inch round cake pans and line the bottoms with parchment.
2. Mix the batter: Whisk the flour, sugar, cocoa, baking powder, baking soda, and salt in a large bowl. Add the eggs, buttermilk, oil, and vanilla; mix until combined. Carefully stir in the hot coffee or water, scraping the bowl to incorporate any dry flour. The batter will be fairly thin.
3. Bake the layers: Divide the batter evenly among the pans. Bake uncovered on the center rack, starting to check at 24 to 25 minutes. The layers will usually take about 25 to 32 minutes, but pan depth and oven behavior can change the timing. They are done when a toothpick inserted near the center comes out clean or with a few moist crumbs, and the centers spring back lightly without wobbling. If wet batter remains, keep baking and check again.
4. Cool completely: Let the cakes cool briefly in their pans, then turn them out onto wire racks. Do not frost them until they are cool throughout. If needed, level domed tops with a serrated knife once cool.
5. Make the peanut butter frosting: Beat the softened butter and peanut butter until smooth. Beat in the powdered sugar, then add the cream or milk a little at a time until the frosting spreads easily and holds a soft ridge. Reserve enough for a piped border; use the rest for the two filling layers.
6. Make the chocolate frosting: Beat the softened butter and cocoa until combined. Add the powdered sugar, then gradually beat in the cream or milk until the frosting is smooth and easy to spread.
7. Fill and stack: Place one cake layer on a serving board. Spread half the peanut butter filling evenly over it, close to the edge without letting it bulge. Add the second layer and repeat with the remaining filling. Set the third layer on top, keeping the stack level.
8. Frost and decorate: Spread a thin crumb coat of chocolate frosting over the top and sides. If the cake feels soft or shifts, chill it briefly until steadier. Cover it with the remaining chocolate frosting, then pipe the reserved peanut butter frosting around the top edge. Cluster the chopped peanut butter cups near the center, leaving the border visible.
9. Serve: Cut and remove a large wedge to reveal the three chocolate layers and two peanut butter filling bands. The cake makes 12 to 16 slices.

How to Keep the Filling and Frosting Neat

Even filling layers help the cake sit level. Avoid piling peanut butter frosting at the edges, where the weight of the next layer can squeeze it out. The chocolate crumb coat catches loose crumbs before the final coat goes on.

Use conventional creamy, no-stir peanut butter for filling that spreads smoothly and holds its shape when piped. Natural peanut butter varies in consistency and can make the frosting thin or oily.

Make-Ahead and Storage

Wrap completely cooled cake layers well and freeze for up to 3 months; thaw them before assembling. The frostings can also be made ahead. Bring them back to a workable temperature before filling and coating the cake.

Keep the finished cake covered in the refrigerator. For best quality, plan to serve it within about 5 days, though storage guidance varies. Let refrigerated slices sit briefly at room temperature so the buttercream softens; no reheating is needed.

Nutrition

Approximate nutrition per serving, based on 1 of 14 slices: 1,000 calories, 11g protein, 53g fat, and 128g carbohydrates. Approximate values per 100g: 435 calories, 5g protein, 23g fat, and 56g carbohydrates. Values vary with slice size, the choice of cream or milk, and the ingredients used.