This cake features a peanut butter cake, topped with peanut butter frosting. The whole cake is then topped with chocolate ganache. To achieve the ridges that give this cake the peanut butter cup look, I used the origami technique of pouring ganache over accordion-folded card stock and pressing it to the sides of the cake. Once the ganache was set, I removed the paper to reveal the ridges. The whole process is easier than it seems! To get the slant, I baked my batter in a 10-inch and an 8-inch pan and then trimmed the sides of the larger cake on a diagonal. You could bake in two 8 or 9-inch pans and do a cake with straighter sides. To get flat layers, I use Wilton Baking strips during the baking. If you don’t have these, you will need to trim the tops of your cakes to make them flat when they have cooled.
Ingredients
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For the Peanut Butter Cake
- For the Peanut Butter Frosting
- For the Chocolate Ganache
- Special equipment
Instructions
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For the Cake
- Preheat oven to 350F/180C. Grease, flour and line 2 round baking pans. (I used a 10-inch and an 8-inch, but you could use two 8 or 9-inch).
- Combine, water, peanut butter and 1/2 cup (120 ml) buttermilk in a medium saucepan. Cook over medium heat until the mixture is well combined. Remove from heat and set aside.
- In a small bowl, whisk together flour, baking soda and salt. Set aside.
- In a large bowl, whisk together eggs, sugar and vanilla until well combined. Pour in peanut butter mixture and whisk to combine. Add flour mixture and stir until combined.
- Pour into prepared pans and bake for 20-25 minutes until a toothpick inserted in the centre comes out clean. Let cool in pans for 10 minutes then turn out onto racks and remove the parchment paper. Let the cakes cool completely. For the Frosting
- Whip together peanut butter, butter, vanilla and salt until light and fluffy, about 3 minutes.
- Add powdered sugar and beat until well combined and a spreadable consistency, about 3 minutes. If the frosting is too thick, add cream, 1/2 tbsp at a time until you reach the desired consistency. For Assembly
- Once the cakes have cooled, trim the tops so that they are flat if necessary. If using two sizes of cake, trim the sides of the larger cake on a diagonal so that they go in toward the smaller cake, which will be on the bottom.
- Place the smaller cake on a cake board or place. Spread with 1 cup of frosting. Place the larger cake on top. Frost the top and sides of the cake, trying to get the frosting as smooth as possible. Freeze the cake for 30-60 minutes until the frosting has hardened. For the Chocolate Ganache
- Place the chopped chocolate in a microwave-safe bowl (you will occasionally need to reheat the chocolate to soften it.)
- Bring the cream to a simmer over medium heat then pour it over the chocolate. Let sit for 5 minutes to let the chocolate soften, then stir with a spatula until you have a smooth ganache. Let cool for 15 minutes until it becomes thicker and is a more spreadable consistency.
- Spread a thin layer of ganache over the top and sides of the cake. Place the cake in the fridge to set slightly while you prepare the origami ganache strips.
- Place your folded strips of paper on a baking sheet then pour ganache over the strips, spreading it to coat the strips in an even layer that goes to the top of each accordion fold. (I've linked a video of this in the notes.) Make sure to save ganache for spreading over the top and any needed touch-ups at the end.
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- Put the cake in the fridge to set for 30 minutes. Once the ganache has set a bit, use scissors to cut off the parts of the strips that go above the top of the cake. You can save the ganache that is cut off for later use.
- Warm up your reserved ganache in the microwave for 10-15 seconds until pourable. Pour about 1/2 cup of ganache over the top of the cake and spread it evenly all the way to the paper sides of the cake. Put the cake in the fridge to firm up for 1 hour.
- Once the ganache is completely set, gently peel the paper off of the cake. Touch up any gaps in the ganache with some of your reserved ganache. Smooth any bumps in the ridges by pressing them gently with some parchment paper. Gently mooth the top with an offset spatula or butter knife.
Notes
To see a video of how to spread the ganache on the folded paper click here.