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Decadent Chocolate Peanut Butter Layer Cake Recipe

This indulgent chocolate peanut butter cake features layers of moist chocolate cake filled and frosted with creamy peanut butter frosting. It’s a peanut-butter-lover’s dream—rich, decadent, and delicious.

Slice of chocolate peanut butter cake with a bite taken out of it.

Chocolate and peanut butter are a classic pairing, and this chocolate peanut butter cake balances them perfectly. The chocolate layers are fudgy and exceptionally moist, while the peanut butter frosting is smooth, rich and not overly sweet—just full of peanut-butter flavor. If you love peanut butter cups, this cake is the birthday cake of your dreams.

For the Chocolate Cake

A few key ingredients make this cake especially tender and flavorful:

  • Vegetable oil keeps the cake moist for days without leaving an oily taste.
  • Buttermilk gives the crumb a soft, tender texture.
  • Boiling water “blooms” the cocoa powder, intensifying the chocolate flavor.

You can mix this batter by hand with a whisk or use an electric mixer. Use a large bowl—there’s a lot of batter.

  1. Whisk together the dry ingredients so the leavening is evenly distributed.
  2. In a separate bowl, whisk the oil, sugar, eggs, vanilla and buttermilk until combined.
  3. Gently combine the wet and dry ingredients, making sure there are no lumps; the batter will be thick.
  4. Carefully whisk in the boiling water; the batter will thin considerably. Scrape the bottom of the bowl so everything is incorporated.

4 step process of making chocolate cake batter

Divide the batter evenly between prepared pans and bake.

A Few Notes About Pan Sizes

This recipe was tested in three 8-inch (20 cm) round cake tins; baking time was about 18–22 minutes at 350°F (180°C). Other options:

  • Two 8-inch (20 cm) pans with at least 2-inch sides — bake 25–30 minutes at 350°F.
  • Two 9-inch (23 cm) pans — bake about 22 minutes at 350°F.
  • If you prefer cupcakes, use a dedicated cupcake recipe adapted for peanut butter frosting.

A 3-layer chocolate cake with peanut butter frosting.

For The Peanut Butter Frosting

The frosting is thick, creamy and loaded with peanut butter flavor. Adjust the powdered sugar to taste if you prefer it sweeter or less sweet. Use smooth, commercial-style peanut butter (such as Skippy, Jiff or similar) — do not use natural or homemade peanut butter that separates, or the frosting may split and become oily.

Assembling the Cake

Layering a cake is straightforward when you follow a few simple tips:

  1. Make sure the cake layers are completely cool before you assemble the cake.
  2. If the tops are domed, level them with a serrated knife so the layers stack evenly.
  3. Place a few strips of parchment or wax paper around the cake board or plate to catch excess frosting while you decorate; remove them when finished.
  4. Do a crumb coat: spread a thin layer of frosting around the sides to trap crumbs, chill the cake for about 30 minutes to set the crumb coat, then apply the final thicker coat with decorative swirls.

Collage of 2 photos of assembling a chocolate peanut butter layer cake.

Moist chocolate cake and creamy peanut butter frosting combine for a luscious layered dessert that’s perfect for celebrations or any time you want an over-the-top treat.

Slice of chocolate peanut butter layer cake.

Slice of chocolate peanut butter cake on a plate.

Chocolate Peanut Butter Cake

This decadent cake has layers of moist chocolate cake with creamy peanut butter frosting—a peanut butter lover’s delight.
Prep: 1 hr
Cook: 22 mins
Cooling: 2 hrs
Total: 3 hrs 22 mins
Servings: 14 pieces

Equipment

  • three 8-inch (20 cm) round cake tins

Ingredients

Chocolate Cake

  • 2 1/2 cups all-purpose flour (312.5 g)
  • 1 cup cocoa powder (80 g)
  • 2 teaspoons baking soda
  • 1 teaspoon baking powder
  • 1/2 teaspoon salt
  • 2/3 cup vegetable oil (160 ml)
  • 2 1/2 cups granulated sugar (500 g)
  • 3 large eggs
  • 2 teaspoons vanilla extract
  • 1 1/4 cups buttermilk* (300 ml)
  • 1 cup boiling water (240 ml)

Peanut Butter Frosting

  • 1 3/4 cup unsalted butter (395 g), softened to room temperature
  • 1 1/4 cup smooth peanut butter (300 g)*
  • 1 teaspoon vanilla extract
  • 5–6 cups powdered sugar (550–660 g), sifted
  • 3–5 tablespoons whipping cream or milk

Instructions

Chocolate Cake

  1. Preheat the oven to 350°F (180°C). Line the bottoms of three 8-inch tins with parchment and lightly grease the sides, dusting with cocoa powder.
  2. In a large bowl whisk together flour, cocoa powder, baking soda, baking powder and salt. Sift the cocoa if it’s lumpy.
  3. In another bowl whisk oil, sugar, eggs, vanilla and buttermilk until combined.
  4. Gently whisk the wet ingredients into the dry ingredients until smooth and lump-free; the batter will be thick.
  5. Carefully whisk in the boiling water (or beat on low with a mixer). The batter will thin out.
  6. Divide the batter evenly among the three pans (weigh them if you want perfectly even layers).
  7. Bake 18–22 minutes, or until a toothpick inserted in the center comes out clean and the cakes begin to pull from the pan sides.
  8. Cool in pans for at least 30 minutes, then invert onto a wire rack to finish cooling completely.

Peanut Butter Frosting

  1. In a large bowl, beat the butter until smooth.
  2. Add the peanut butter and beat until smooth and combined.
  3. With the mixer on low, beat in 2 cups of powdered sugar and the vanilla.
  4. Add the remaining powdered sugar about 1 cup at a time, alternating with 1–2 tablespoons of cream or milk until you reach the desired sweetness and a thick, spreadable consistency.

Assembling the Cake

  1. Make sure the cake layers are completely cool.
  2. Level any domed tops with a serrated knife so the layers stack evenly.
  3. Place the first layer bottom-side up on your serving plate and spread a layer of frosting on top. Repeat with the second layer, then top with the third.
  4. Apply a thin crumb coat around the sides and chill for about 30 minutes to set.
  5. Frost the top and sides with a thicker final layer, using swirls if desired. Optionally decorate with peanut butter candies.
  6. For clean slices, use a thin knife and wipe it between cuts.

Notes

  1. Pan alternatives:
    • Two 8-inch pans with 2-inch sides — bake 25–30 minutes at 350°F.
    • Two 9-inch pans — bake about 22 minutes at 350°F.
    • For cupcakes, adapt the recipe to a cupcake format and bake accordingly.
  2. If you don’t have buttermilk: combine 1 1/4 cups milk with 1 tablespoon lemon juice or white vinegar. Stir and let sit 5 minutes before using.
  3. Use smooth, non-separating commercial peanut butter for the frosting; natural peanut butter may cause separation.
  4. Storage:
    • Unfrosted cake layers: room temperature in an airtight container for 2 days or refrigerated up to 5 days.
    • Frosted leftovers: refrigerated and covered for up to 4 days.
    • Unfrosted layers freeze up to 2 months in a freezer bag; thaw in the fridge.
    • For best results, bake the cake layers a day ahead, store unfrosted at room temperature overnight, then frost and assemble the day you plan to serve.
  5. Nutrition information is an estimate based on 14 slices and using all the frosting.

Nutrition

Calories: 871 kcal; Carbohydrates: 105 g; Protein: 12 g; Fat: 49 g; Saturated Fat: 27 g; Sugar: 81 g; Sodium: 390 mg (per slice, estimate).