This is basically a peanut butter cup in cake form! A super fudgy dark chocolate cake, a peanut butter filling, and frosted with a chocolate Swiss meringue buttercream. It is the ultimate celebration cake and so delicious.
Tell me about this recipe!
- This cake is made of super fudgy and rich chocolate cake layers. The color of the cake is so dark because of the hot coffee added to the batter.
- The filling is made of peanut butter, golden syrup, butter, and powdered sugar.
- It is frosted with a chocolate Swiss meringue frosting, which is so creamy and light.
The printable recipe card with the full list of ingredients and instructions can be found at the bottom of this post.
- Cocoa Powder while some cakes might have you use melted chocolate, I’m using cocoa powder, but make sure to use the highest quality you can find!
- Buttermilk I love using buttermilk for my cakes to give you that extra tang, but I know not everyone has it hanging around. The trick? Add 1 tablespoon of vinegar or lemon juice for every cup of milk, leave it for 5 minutes, and you’ve got buttermilk!
- Peanut Butter Don’t use a natural peanut butter with oil in it, as that will make the filling too runny.
- Hot Coffee this is what ‘blooms’ the cocoa powder and gives us that extra dark colour. If you don’t want to use coffee, you can replace it with hot water instead.
Making the Recipe
One: Whisk together all of the dry ingredients in a stand mixer until well combined.
Two: In a large jug, whisk together the buttermilk, oil, eggs and vanilla.
Three: With the mixer running on low, slowly pour in your wet ingredients. Then pour in your hot coffee. The batter is going to be very thin, so make sure you have the speed on low the whole time so it doesn’t splash.
Four: Pour your batter out into three 8 inch cake pans. If you only have two pans, weigh out the batter using a scale (each pan will have 22 ounces/600 grams). Keep the batter for one of the layers to the side, and bake the first two. Once the cake has cooled a bit, remove the cake and regrease the pan. Then pour in the remaining batter. Bake at 350 degrees for 35-40 minutes.
Five: Make your Swiss meringue by filling a medium saucepan with an inch of water and bringing to a boil. Place your stand mixer bowl over (not letting it touch the water!) and whisk the egg whites, sugar, salt and cream of tartar together. Whisk until there are no more granules (use your fingers to check, be careful as it may be hot) then place the bowl into your stand mixer. Whip up the egg white mixture until you get a stiff, glossy meringue. It may take about 8-10 minutes.
Six: Once the meringue is stiff and glossy, and the bowl is cool to the touch, start adding the butter cube by cube while the mixer is still on high speed. This will take another 8-12 minutes.
Seven: Once the mixture looks smooth and all the butter has been added, pour in your melted chocolate while the mixer is on low speed. Your buttercream is now ready!
Eight: In a stand mixer or in a bowl with a hand held mixer, whisk together all the peanut butter filling ingredients except for the powdered sugar. Whip together until smooth and creamy.
Nine: Add the powdered sugar bit by bit until you have a thick consistency.
Ten: Assemble the cake. Start with the first layer, and use a piping bag to pipe out a circle of buttercream along the outer edge – this will stop the peanut butter filling from seeping out. Then, take half of the peanut butter filling and use a small offset spatula to spread it on top. Repeat with the second layer.
Eleven: Coat the cake in a thin layer of buttercream and chill for about 20 minutes. Then, frost the entire cake.
Twelve: I use a small spoon to create swoops and swirls, creating a nice texture on the frosting. Finally, add some chopped miniature peanut butter cups to the top of the cake!
- I highly recommend using a weighing scale and measuring out your ingredients the metric way. It makes a huge difference to your baking and is the most accurate way to bake!
- I like to make my Swiss meringue buttercream first so it can chill for a little bit in the fridge. This is important if your kitchen is too hot! Once my buttercream is chilling out (literally), I get started on my filling. This filling is best used immediately, so once that is finished I am ready to go.
- Make sure all of your ingredients are at room temperature before you get started. Pull everything out at least 2 hours before you want to start baking.
Frequently Asked Questions
I always bake my cakes the night before. Less stress on the way, plus you know your cakes will be cool enough to frost.
his recipe uses three 8″ pans. You could use a 9″ pan instead but your layers will be thinner and you will have to adjust the baking time. I also make sure to weigh out my batter in all the pans so they’re all even.
The secret to getting that perfect slice? A hot knife! I boil water and pour it into a tall glass. I use a pretty large knife, get it super hot, and then wipe off the water with a tea towel. This will give you that picture perfect slice!
I recommend storing the cake in the fridge for up to 5 days. Bring your slices to room temperature before eating.
Other Cake Recipes to Try:
Chocolate and Peanut Butter Layer Cake
- 3 x 8" pans
- 1 ½ cups hot coffee
- 1 cup cocoa powder
- 2 ½ cups granulated sugar
- 1 teaspoon vanilla extract
- 1 teaspoon kosher salt
- 3 eggs
- 2 ¾ cups flour
- 3 teaspoon baking soda
- 1 ½ teaspoon baking powder
- 1 ½ cups buttermilk
- 1 cup vegetable oil
Peanut Butter Filling
- ½ cup unsalted butter room temperature
- ½ cup peanut butter
- 1 ½ tablespoon golden syrup
- ¼ teaspoon kosher salt
- ¾ cup powdered sugar sifted
Swiss Meringue Buttercream
- 8 ounces dark chocolate melted and room temperature
- 1 cup granulated sugar
- 5 egg whites
- 1 ⅓ cups unsalted butter room temperature
- ½ teaspoon kosher salt
- ¼ teaspoon cream of tartar
- Preheat oven to 350°F/175°C. Grease 3 8-inch cake pans with butter, then line the bottoms with parchment paper.
- Combine the flour, cocoa powder, sugar, baking powder, baking soda, and salt in the bowl of a stand mixer, using the paddle attachment. Set aside. In a large jug, combine the buttermilk, oil, eggs and vanilla.
- While the mixer is on low speed, slowly pour in the wet ingredients. While mixer is till running, slowly add the coffee and mix. Your batter will be very thin.
- Pour the batter into the prepared pans. Bake for 35-40 minutes, until a toothpick comes out clean when inserted.
- Allow the cakes to cool completely before removing from pans.
Swiss Meringue Frosting
- Fill a medium saucepan with an inch of water and bring to boil. Combine the sugar, salt, cream of tartar and egg whites in a large mixing bowl (if you have a stand mixer, you'll want to use that bowl), set the bowl above the simmering water.
- Heat, whisking constantly, until the sugar dissolves. The mixture will go from a yellowy, granular substance to white and opaque, this takes about 5 minutes. Using a thermometer, it should read 115°F. If you don't have a thermometer, when you pull the whisk up feel the mix with your fingers – if it is no longer grainy then it is ready for the next step.
- Put the bowl into your stand mixer with a whisk attachment and beat on medium-high until you get a stiff, glossy meringue – about 8-10 minutes. You'll want to be beating the mixture until the bowl is completely cool.
- Add butter one piece at a time, allowing it to incorporate fully, while still at medium-high speed. This should take 8-12 minutes. When you've added all the butter and the mixture looks smooth, slowly pour in the chocolate. Give it one final mix using a rubber spatula to make sure all of the chocolate is incorporated.
Peanut Butter Filling
- Add all of the ingredients except the icing sugar in a large bowl and mix using a hand held mixer. Mix until pale and creamy, 2-3 minutes.
- Add the icing sugar a little at a time, beating well between each addition.