Peanut butter and chocolate are an elite combination. This particular recipe is double the chocolate with both chocolate cake layers and a fudgy chocolate ganache icing. After spreading on the chocolate ganache icing, we add a thick layer of our favorite creamy peanut butter buttercream. If you are a fan of peanut butter and chocolate you will absolutely love this fudgy chocolate peanut butter cake.
Why This is the Best Chocolate Peanut Butter Cake
There few combinations as iconic as chocolate and peanut butter. To make this cake even more iconic, we have gone beyond just combining our favorite chocolate cake with a peanut butter icing, but we also add in a fudgy chocolate ganache. This combines with our Swiss-style peanut butter buttercream for the ultimate peanut butter chocolate cake. These are truly 3 of our favorite base recipes combined into one. We love every single component of this cake and combined it is truly incredible.
Ingredient Notes to Make the Best Cake
- Dutch-Processed Cocoa Powder: This gives the cake its deep, dark color and a strong chocolate flavor that isn’t too acidic.
- Hot Coffee: Trust us, the cake won’t taste like coffee. Instead what happens is the hot liquid allows the cocoa powder to bloom which makes the chocolate flavor more intense and creates a velvety crumb in the cake.
- Buttermilk: This is the key to a moist chocolate cake. There is a reason we use this in just about all of our cakes. The acidity reacts with the baking soda to create a light, tender cake that stays fresh for days. It’s really a non-negotiable for us. Buttermilk just belongs in cake layers.
- Creamy Peanut Butter: For the smoothest buttercream, we recommend a standard creamy brand (like Skippy or Jif). Natural peanut butters tend to separate and can make the frosting grainy.
Tips for the Perfect Fudgy Ganache
The ganache is what creates this cake’s chocolate fudge layer. We often see comments that this layer is too thin or not spreadable, but it can also get hard and grainy if left in the fridge too long. A few tips to help: Let the ganache set in the fridge until it is firm but still spreadable. Keep an eye on it stirring every 20-30 minutes. If it’s too runny, the peanut butter buttercream will slide off, but if it sets too long, it will become grainy.
Frequently Asked Questions (FAQ) – Fudgy Chocolate Peanut Butter Cake
Can I make this as a layer cake instead of a sheet pan?
Absolutely! While this recipe is optimized for a 16×10 sheet pan, you can bake it in two 8-inch round pans and cut the layers in half (this would be 4 layers instead of 3 so your icing layers will be thinner). Just keep an eye on the bake time, as deeper pans will require a few extra minutes in the oven.
Does this cake need to be refrigerated?
Because of the heavy cream in the ganache and the egg whites in the buttercream, we recommend storing this cake in the refrigerator. Although it’s best day of and can be left out for a few hours (depending on the temperature). However, for the best texture, let a slice sit at room temperature for 15–20 minutes before serving so the buttercream softens up. It’s also really dangerous after being frozen.
Why is my buttercream curdling?
If your peanut butter buttercream looks curdled when you add the butter, keep whisking. Usually, a few more minutes on medium-high speed will bring the emulsion back together into a silky smooth frosting.
Peanut Butter Fudge Cake
Ingredients
Chocolate Cake:
- 1 ¾ cups all-purpose flour 210 g
- 2 cups granulated sugar 400 g
- ¾ cup unsweetened cocoa powder preferably dutch processed 75 g
- 2 teaspoons baking soda 10 ml
- 1 teaspoon baking powder 5 ml
- 1 teaspoon salt ½ if morton 5 ml
- 2 large eggs
- 2 teaspoons vanilla extract 10 ml
- 1 cup buttermilk 240 ml
- ½ cup oil canola or vegetable 120 ml
- 1 cup hot coffee 240 ml
Peanut Butter Buttercream:
- 8 ounces salted butter room temperature
- 8 ounces granulated sugar
- 4 ounces egg whites
- ½ teaspoon salt
- 3/4 cup creamy peanut butter we used skippy, 200 g
Chocolate Ganache:
- 5 oz chocolate
- 4 tablespoons butter 57 g
- 3/4 cup sugar 150 g
- 3/4 cup heavy cream 180 ml
- 2 teaspoons vanilla 10 ml
- Pinch of salt
Instructions
Cake:
- Combine the sugar, flour, cocoa powder, baking soda, baking powder, and salt into a bowl. Stir together with a whisk until evenly combined
- Add the vanilla, eggs, buttermilk, and oil and stir until combined
- Once combined, add the hot coffee. Stir quickly to ensure the hot coffee is evenly distributed. The batter will be very thin
- Pour the batter into a greased and floured 16”x10” sheet pan and cook for ~15-20 minutes (ovens vary so test with a toothpick in the center and remove when it comes out clean) 350 F – make sure a toothpick comes out clean
- Set aside to cool
Ganache:
- To make the ganache, add chocolate, butter, salt, and vanilla into a bowl. Set asideIn a small pan over medium heat, heat cream and sugar until hot but just before boiling
- Pour the heated cream and sugar over the bowl of chocolate and let it set for 1 minute. Stir until smooth
- Set in the fridge until cooled but not hard. This will take around 30 minutes – 1 hour. It should be very firm to keep the cake stable
Peanut Butter Buttercream:
- Cut the softened butter in tablespoon pieces.
- Add 2 inches of water into a saucepan that fits the bowl of a stand mixer on top without touching the water. After the water is simmering, add the sugar, egg whites, and salt. Whisk to combine and continue to simmer, ensuring the water does not touch the bowl. Keep heating the mixture until the sugar is dissolved (it will be about 120 degrees)
- Place the bowl in the stand mixer and whisk on high speed until mixture is thick and glossy. It should hold very stiff peaks.
- Reduce the speed of the mixer to medium and add the butter one tablespoon at a time until incorporated. Reduce the speed to low and add the peanut butter. Turn up the speed to medium until well incorporated. Set aside
Assembly:
- When all components are ready, cut the cake into 3 even rectangles, each piece should be ⅓
- Spread a thin layer of the ganache frosting (we also like to pipe on a boarder of ganache to keep the peanut butter icing enclosed.) After adding the ganache, then place half the peanut butter frosting on top. Repeat again. Top with a thin layer of the ganache icing on top. We choose to leave the sides ope, but trim the edges before serving to it's a clean rectangle with open sides
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