Chocolate Peanut Butter Cake

4 from 2 votes

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This decadent chocolate peanut butter cake has layers of moist chocolate cake with creamy peanut butter frosting. A peanut butter lover’s delight – this recipe is over the top delicious. 

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

Chocolate and peanut butter are a classic combination, and this chocolate peanut butter cake is truly the best of both. The chocolate cake is rich, fudgy and incredibly moist. It’s sandwiched with peanut butter frosting that’s not too sweet, but very peanut buttery. The cake is (obviously) very rich, but it’s the birthday cake of your dreams if you love peanut butter cups.

For the Chocolate Cake

The cake itself is extremely moist and flavorful because of a few key ingredients:

  • Using oil keeps the cake moist for days. Don’t worry, you won’t taste the oil at all because it’s masked by the cocoa powder.
  • Buttermilk gives the cake a ridiculously soft cake crumb. It’s my go-to for chocolate cake recipes.
  • Boiling water helps to bring out the flavor of the cocoa powder. This is called “blooming” the cocoa.

You can actually make this batter entirely by hand with a metal whisk, or do it using an electric mixer. Whatever you choose though, just make sure you use a very big bowl. There’s a lot of batter.

  1. First, you’ll whisk together the dry ingredients. This is to ensure that the baking powder and baking soda are evenly distributed throughout the batter.
  2. Then in a separate bowl, you’ll whisk together the oil, sugar, eggs and buttermilk.
  3. Carefully whisk/beat the wet ingredients into the dry ingredients. You want to ensure that you don’t have lumps in the batter. At this stage  the batter will be quite thick.
  4. Then, very, very carefully – whisk/beat in the boiling water. The batter will be quite thin at this point. Make sure that you don’t have batter sticking to the bottom of the bowl.

4 step process of making chocolate cake batter

Then you’ll divide the batter evenly between your prepared cake pans, and pop them in the oven to bake.

A Few Notes About Pan Sizes

I used three 8-inch (20 cm) round cake tins for this chocolate peanut butter cake. The bake time was around 20 minutes at 350F degrees. Alternatively, you could use:

  • two 8-inch (20 cm) round cake tins – just ensure they’re sides are at least 2 inches tall. The bake time will be around 25-30 minutes at 350F.
  • two 9-inch (23 cm) round cake tins will bake for about 22 minutes at 350F degrees.
  • for cupcakes, I recommend this recipe

A 3-layer chocolate cake with peanut butter frosting.

For The Peanut Butter Frosting

The frosting is thick, peanut buttery, and very creamy. You can adjust the amount of sugar slightly, depending on how sweet you like it. When making peanut butter frosting, the most important thing is to use smooth, commercial-style peanut butter (something like Kraft, Skippy or Jiff). Do not use natural, homemade or anything that can separate. Otherwise, your frosting can separate and leave pools of oil.

Assembling the Cake

I promise, cake layers are not as complex as they might seem. Here’s my main tips about assembling a layer cake:

  1. Ensure your cake layers are completely cooled before assembling the cake.
  2. If your cake layers are domed (they most likely will be), use a serrated knife to gently saw off the rounded top.
  3. Place a few strips of wax paper or parchment paper around the outside edges of your plate (the cake will just slightly go overtop of them). This helps to keep your plate clean. Then wiggle them out after you’re done decorating.
  4. Do a crumb coat around the sides. A crumb coat is a very thin layer of frosting that helps to seal in all the cake crumbs. It may look “dirty”. After doing a crumb coat, place the cake in the fridge for about 30 minutes for the frosting to harden. Then frost the cake again with swirls of frosting. This way, the final coat of frosting won’t have cake crumbs in it.

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

Moist chocolate cake, creamy peanut butter frosting – this chocolate peanut butter cake has layers of decadence for the absolute perfect peanut butter dessert!

For more delicious layer cake recipes, be sure to try:

Slice of chocolate peanut butter layer cake.

Slice of chocolate peanut butter cake on a plate.
4 from 2 votes

Chocolate Peanut Butter Cake

This decadent chocolate peanut butter cake has layers of moist chocolate cake with creamy peanut butter frosting. A peanut butter lover's delight - this recipe is over the top delicious. ing from Just So Tasty
Prep: 1 hour
Cook: 22 minutes
Cooling: 2 hours
Total: 3 hours 22 minutes
Servings: 14 pieces
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Equipment

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

Ingredients 

Chocolate Cake

  • 2 1/2 cups all-purpose flour (312.5 grams)
  • 1 cup cocoa powder (80 grams)
  • 2 teaspoons baking soda
  • 1 teaspoon baking powder
  • 1/2 teaspoon salt
  • 2/3 cup vegetable oil (160 ml), canola oil works too
  • 2 1/2 cups granulated sugar (500 grams)
  • 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 grams), softened to room temperature (not melty)
  • 1 1/4 cup smooth peanut butter (300 grams)*
  • 1 teaspoon vanilla extract
  • 5-6 cups powdered sugar (550 - 660 grams), sifted
  • 3-5 tablespoons whipping cream , or milk

Instructions 

Chocolate Cake

  • Preheat the oven to 350 F (180 C) degrees.
  • Line the bottom of three 8-inch round cake tins with rounds of parchment paper. Lightly grease the sides and sprinkle with cocoa powder.
  • In a very large bowl, whisk together the flour, cocoa powder, baking soda, baking powder and salt. If the cocoa powder is very lumpy, sift it first.
  • In a separate large bowl, whisk together the oil, sugar, eggs, vanilla extract and buttermilk.
  • Carefully whisk the wet ingredients into the dry ingredients. This can also be done with an electric mixer on low speed. Ensure there are no lumps - the batter will be thick.
  • Very carefully whisk (or beat with an electric mixer) the boiling water into the cake batter. It will be quite a bit thinner now.
  • Divide the cake batter evenly between the 3 pans. You can weigh the pans to ensure they're the same size.
  • Bake in the preheated oven for 18-22 minutes, or until an inserted toothpick comes out clean and the cakes are starting to pull away from the sides of the pans.
  • Remove from the oven and cool the cakes in their pans for at least 30 minutes, then gently invert the cakes and continue cooling on a wire rack.

Peanut Butter Frosting

  • In a very large bowl, beat the butter until smooth.
  • Mix in the peanut butter until smooth.
  • With the mixer on low speed, beat in 2 cups powdered sugar and the vanilla extract.
  • Mix in the rest of the powdered sugar about 1 cup at a time, alternating with 1-2 tablespoons of whipping cream (or milk) until the desired sweetness and consistency is reached. It should be thick, but not as thick as peanut butter.

Assembling the Cake

  • Ensure that the cake layers are completely cooled first.
  • Using a serrated knife, gently saw off the domed top of each cake so that the cake layers are flat instead of rounded on top.
  • Place 1 cake layer, bottom side up, on the plate you plan to serve the cake on. Frost the top with a layer of frosting. Place the 2nd cake layer on top (bottom side up) and frost the top. Place the 3rd layer on top.
  • Carefully, frost the sides of the cake with a very thin layer of frosting. This is the crumb coat. If cake crumbs come up, don't worry. Place the cake in the fridge for about 30 minutes for the crumb coat to firm up.
  • Remove the cake from the fridge. Frost the top and sides with a thick layer of frosting, swirling the frosting as you go.
  • Optionally, decorate the top with peanut butter candies.
  • Slice the cake using a thin knife. For clean cuts, wipe off the knife after each slice.

Notes

  1. For alternative pan sizes, this cake can be made in:
    • two 8-inch (20 cm) round cake tins - just ensure they're sides are at least 2 inches tall. The bake time will be around 25-30 minutes at 350F.
    • two 9-inch (23 cm) round cake tins will bake for about 22 minutes at 350F degrees.
    • for cupcakes, I recommend this recipe
  2. If you don't have buttermilk, measure out 1 1/4 cups whole milk (or 2%). Add in 1 tablespoon of freshly squeezed lemon juice or white vinegar. Give it a stir and let it sit for 5 minutes before using.
  3. Do not use natural or homemade peanut butter, otherwise the frosting can separate.
  4. Nutrition information is an estimate only and based on 1 slice, assuming the cake is cut into 14 equal-sized pieces and all the frosting is used.
  5. Storage & Make-Ahead Tips:
    • Unfrosted cake can be wrapped tightly and stored in an airtight container at room temperature for 2 days, or in the fridge for up to 5 days. 
    • Store leftovers covered in the fridge for up to 4 days.
    • Unfrosted cake layers can be wrapped tightly and placed in a freezer bag or container and frozen for up to 2 months. Thaw in the fridge. 
    • I typically make the chocolate cake the day before I plan to serve it. Store the unfrosted cake layers in an airtight container at room temperature overnight. Then I make the frosting and assemble the cake the day I plan to serve it. Cover the cake and store at room temperature until you plan to serve it that evening. 

Nutrition

Calories: 871kcal, Carbohydrates: 105g, Protein: 12g, Fat: 49g, Saturated Fat: 27g, Trans Fat: 1g, Cholesterol: 108mg, Sodium: 390mg, Potassium: 352mg, Fiber: 4g, Sugar: 81g, Vitamin A: 850IU, Vitamin C: 1mg, Calcium: 74mg, Iron: 3mg
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2 Comments

  1. 3 stars
    I just made this cake this evening to take to work tomorrow. I’ll come back with the verdict but from the top of the cake we cut off and the frosting, it tasted pretty good.
    I made a grape jelly syrup to brush on the layers and only made a two layer 9” cake. Batter was a little much for the pans and I had to bake if for close to an hour.
    I used mini Reese’s PB cups around the cake and 3 of each color (yellow, orange and brown) in between each cup. Looks very nice too.