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Chocolate Peanut Butter Cup Layer Cake

by Haley
Chocolate Peanut Butter Cup Layer Cake - Flour Covered Apron

This chocolate peanut butter cup layer cake pairs together a classic combination. With three layers of rich chocolate cake, creamy peanut butter frosting, mini peanut butter cups, and chocolate ganache, it is one yummy cake!

Oh my goodness, I’m so excited to share this epic chocolate peanut butter cup layer cake with you! I keep making it over and over again because I have the biggest weakness for this dreamy combination, and it satisfies all my peanut butter cup cravings. And I know I’m not alone here because so many of you have asked for the recipe!

In fact, as we were preparing to visit our friends in Colorado last month, they actually called ahead to ask if I would pack whatever I needed to bake this specific cake. Unfortunately, my fancy cake turntable wouldn’t fit in my suitcase, but equipped with a few other (smaller) tools, I was ready, and excited to bake for our friends!

Peanut Butter Cup Layer Cake - Flour Covered Apron

We loved every minute of the four beautiful, sunny days we got to spend in Colorado. We hiked a ton, explored farmer’s markets and art festivals, and ate really good food (of course)! And then one night we stayed up late so everyone could teach me how to play Settlers of Catan while I taught them about baking cakes.

The problem was, as I was preparing for the trip, I couldn’t stop worrying about the high altitude. What do you expect from someone who has spent most of her life in the prairie state? I was concerned that my body might react negatively to high altitude, but also really worried about baking. There are so many stories out there about baking fails in high altitude, and I didn’t want to risk a deflated cake. After all, our friends had been practically dreaming about this cake, I knew I couldn’t disappoint them!

Peanut Butter Cup Layer Cake - Flour Covered Apron

So I took to Google and social media to get some recommendations about high altitude baking, and I determined a few small tweaks I could make to my favorite chocolate cake recipe. The whole time the cake was baking, I kept running over and turning on the oven light to check on it. But despite all my anxiety, I ended up being so happy with how it turned out! And our friends loved it too.

The recipe below is written for sea-level, as I know those are the conditions in which most of my readers are baking. This is the recipe I always use when we’re at home. But, I did write down the recipe for a high altitude chocolate cake for any of you who live (or just happen to find yourself baking) in high altitude conditions. You can find it here.

Whether you’re baking at home or while traveling, at sea level or in the mountains… if you love chocolate and peanut butter as much as I do, nothing beats this cake and a tall glass of milk. Promise you’ll love it!

Peanut Butter Cup Layer Cake

Course Dessert


Chocolate Cake

  • 1 3/4 cups flour
  • 2/3 cups unsweetened cocoa powder
  • 1 tablespoon instant espresso powder
  • 1 1/4 teaspoon baking soda
  • 3/4 teaspoon baking powder
  • 1/2 teaspoon salt
  • 1 cup sugar
  • 3/4 cup brown sugar
  • 3/4 cup vegetable oil
  • 1 large egg, room temperature
  • 2 large egg yolks, room temperature
  • 2 teaspoons pure vanilla extract
  • 3/4 cup buttermilk*, room temperature
  • 3/4 cup very hot water

Peanut Butter Frosting

  • 1 cup unsalted butter, softened
  • 1 cup creamy peanut butter
  • 3 1/2 cups powdered sugar
  • 1 teaspoon vanilla
  • 2 tablespoons heavy cream

Chocolate ganache

  • 1 cup semi-sweet chocolate chips
  • 1/2 cup heavy cream
  • 3 tablespoons unsalted butter

For Assembly

  • 1 eight oz package mini peanut butter cups


Chocolate Cake

  1. Preheat oven to 350 degrees Fahrenheit. Line the bottom of three six-inch cake pans with parchment paper, then butter and flour the pans.

  2. Combine flour, cocoa powder, espresso powder, baking soda, baking powder, and salt in a medium size bowl.

  3. In the bowl of a stand mixer, beat the oil and sugars together.

  4. Add the egg, then the egg yolks one at a time, beating until combined after each addition.

  5. Scrape down the sides and add vanilla, mix to combine.

  6. Alternate adding 1/3 of the flour mixture and 1/2 of the buttermilk, starting and ending with the flour. You will have three additions of flour and two additions of buttermilk. Scrape down the sides as needed and mix until incorporated after each addition.

  7. Add the hot water and mix until just combined with a rubber spatula.

  8. Distribute the batter evenly among the three prepared cake pans. Tap each pan gently on the counter to remove extra air bubbles.

  9. Place cake pans in the oven on the middle rack and bake for 35-38 minutes, or until a toothpick inserted into the center of the cake comes out with just a few moist crumbs attached.

  10. Remove cakes from oven and let cool in pans for about 15 minutes. Then, turn layers out onto a wire rack and let cool completely.

Peanut Butter Frosting

  1. Beat softened butter and peanut butter with a hand beater, or the paddle attachment of a stand mixer, until smooth.

  2. Gradually add powdered sugar, with the mixer on low, until combined.

  3. Add vanilla, beat until incorporated.

  4. Add heavy cream, one tablespoon at a time, again beating until incorporated.

  5. Adjust to reach desired consistency by adding more powdered sugar or cream as needed.

  6. Beat on high speed until smooth.

Assembling the Cake

  1. Once cakes are cool, level each layer by using a sharp serrated knife to cut off the rounded domes.

  2. Roughly chop about 1/2 cup of mini peanut butter cups for the filling.

  3. Place bottom cake layer on a cake board, using a small amount of frosting to keep it in place.

  4. Spread a thin layer of frosting on top of the cake, then pipe a dam of peanut butter frosting around the edge of the cake layer using a pastry bag fitted with a large round piping tip.

  5. Fill the center with half of the chopped peanut butter cups.

  6. Spread a small amount of frosting on top of the peanut butter cups to help the next layer stick.

  7. Stack second cake layer on top. and repeat steps 4-6.

  8. Stack third cake layer on top, upside down, so that the bottom of the cake layer forms the top of the cake.

  9. Give the cake a crumb coat of peanut butter frosting and place in fridge for 20 minutes.

  10. Finish frosting the cake with the peanut butter frosting. Reserve extra frosting for piping on top of cake if desired.

  11. Return the cake to the fridge for about 20 minutes.

Chocolate Ganache

  1. While cake is chilling, place chocolate chips in a small heatproof bowl.

  2. Combine heavy cream and butter in a small saucepan over medium heat, stirring frequently, until butter is melted completely and mixture is heated through. Do not let the mixture boil, but you will see bubbles start to form at the edges when it's ready.

  3. Pour cream mixture over the chocolate chips and let stand for 5 minutes.

  4. Stir until smooth, and let cool for a few minutes until it drips fluidly, but slowly off a spoon.

  5. Remove cake from fridge and carefully spoon the ganache around the edges of the cake, pushing it over the edges so that it falls in drips down the side. Work all the way around the edge of the cake before filling in the middle.

  6. Spoon or pour the ganache in the middle of the cake and carefully spread it outward so that it smooths together with your outer edge of ganache. 

  7. Return the cake to the fridge until ganache hardens.

  8. Decorate as desired. I used a large open star tip to pipe large swirls of peanut butter frosting around the edge of the cake, then topped each swirl with a mini peanut butter cup.

Recipe Notes

*You can make your own buttermilk by measuring a scant 3/4 cup of milk (whole or 2%) and adding about 2 teaspoons of lemon juice or vinegar. Stir, and let sit for about 5 minutes before adding to the cake.

Chocolate Peanut Butter Cup Layer Cake - Flour Covered Apron

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