This Chocolate Cake with Peanut Butter Frosting is a rich and moist chocolate cake topped with a smooth and light peanut butter buttercream. It’s chocolate and peanut butter heaven!

There are some flavor combinations that are just made for each other. Chocolate and peanut butter is one of them! I’m a huge fan of sweets with this flavor combination. Be sure to check out my Chocolate Peanut Butter Chip Cookies, No-Bake Cookies, and my Chocolate Peanut Butter Protein Balls!

Overhead photo of a square of chocolate cake covered with peanut butter frosting and melted chocolate squiggles.

Why This Recipe Works

  • Easy homemade chocolate cake with peanut butter frosting. This chocolate cake is so easy to make! Forget the cake box cakes. This homemade chocolate cake uses simple ingredients that you have on hand and is very easy to make.
  • Perfect cake texture. The combination of oil and butter in this recipe results in a moist cake that melts in your mouth! Oil is important in cakes because it can really help increase the moisture since oil is a liquid at room temperature. Plus, chocolate cake with buttermilk also provides a great texture!
  • Rich chocolate flavor. This recipe uses a hefty 3/4 cup of cocoa powder, which provides a nice, rich chocolate flavor that really comes through. We also bloom the cocoa powder. This is when hot water is added to cocoa to help enhance the chocolate flavor.

Ingredient Notes

Ingredients used to make chocolate cake with peanut butter frosting on a gray background.
  • Buttermilk: The buttermilk is an important ingredient for two reasons: for one, it provides excellent moisture and helps produce a tender crumb all because of the acidity. The acidity in buttermilk is also important because it reacts with the baking soda, which helps give a great rise to the cake.
  • Cocoa Powder: I used Dutch-processed cocoa powder. The difference between natural cocoa powder and Dutch-processed cocoa powder is that Dutch-processed is neutral (no acidity) because it’s from cocoa beans that have been washed in an alkaline solution that neutralizes the bitter and acidic flavor. Read more about the Best Cocoa Powder for Baking.
  • Eggs: Eggs are important building blocks in any baking. Eggs work as a binder, meaning they bind together the ingredients. They also provide flavor and act as a leavening agent.
  • Butter: The butter will provide a nice buttery flavor to the cake. Providing fat, it will help provide moisture to the texture of the cake.
  • Vegetable Oil: Using oil in cakes is helpful because it ensures a moist cake. This is because oil is a liquid at room temperature, different from butter which is a solid at room temperature.

Step-by-Step Instructions

  1. Whisk the dry ingredients. In the bowl of a stand mixer fitted with a paddle attachment, stir the flour, baking powder, baking soda, salt, cocoa powder, and sugar.
  2. Add the butter and oil. With the mixer on low speed, add the butter and oil to the dry ingredients until the mixture resembles sand. 
  1. Whisk the vanilla, milk, and hot water. In a large liquid measuring cup, whisk the vanilla, milk and hot water. Pour into the dry ingredients and butter mixture and mix until combined. 
  2. Add the eggs. Add the eggs 1 at a time, mixing after each addition. Spray a 9×13-inch pan with nonstick cooking spray that contains flour. Pour the batter into the prepared pan.
  1. Bake. Bake for 28-34 minutes at 350°F or until a toothpick inserted in the center comes out clean. Remove from the oven and set on a wire rack to cool completely.
  1. Make my peanut butter frosting recipe. Spread the frosting on the cooled cake.
  1. Decorate. Drizzle with melted chocolate. Cut the chocolate cake with peanut butter frosting into squares and enjoy!
Melted chocolate drizzled overtop of a Chocolate Cake with Peanut Butter Frosting.

Recipe Tips

The butter used in the homemade chocolate cake needs to be very soft. If you gently poke your finger into the butter and it leaves a dent, it’s ready to use.

Cocoa powder: Can use natural unsweetened cocoa or Dutch process. I used Dutch process cocoa which is a neutral cocoa powder. Dutch process cocoa is made from cocoa beans that have had their acidity neutralized with an alkaline solution. Just note that if you use unsweetened cocoa powder, the color of the cake will be lighter and the flavor won’t be as rich.

Don’t over bake the cake otherwise it will be dry. 

When mixing the wet ingredients into the dry ingredients, don’t over mix. Over mixing cake batter can result in a tough cake batter, which can affect the bake.

Make Ahead, Storing, and Freezing

Store the cake covered at room temperature for 2-3 days.

You can make this cake ahead of time and store it in the fridge or freezer. Wrap the unfrosted cake in two layers of plastic wrap and freeze for 1 week. If freezing for longer, add a layer of aluminum foil over the plastic wrap and freeze for up to 2 months. Remove from the freezer and place in the fridge to thaw overnight. In the morning, move to the counter to finishing thawing to room temperature, then frost the cake.

If making a day or two in advance, store the unfrosted cake in the fridge wrapped in plastic wrap for 2-3 days.

A square slice of Chocolate Cake with Peanut Butter Frosting on a light colored plate with a brown fork to the side.

Recipe FAQs

How do you keep chocolate cake moist?

Using vegetable oil in cake helps keep it moist because oil is a liquid at room temperature, so when the cake is at room temperature, it will have that added moisture in it. Another trick is to not over mix your batter when you add the dry ingredients and the wet ingredients together. Over mixing cake batter can result in a tough cake once baked.

What makes a cake light and fluffy?

Eggs can help give a nice light texture to cake. Another thing that helps is buttermilk and baking soda. The acidity in the buttermilk reacts to the base of the baking soda, which gives the cake an added rise in the oven.

What does milk do in a cake?

Milk adds moisture, flavor and color to cake.

A slice of chocolate cake topped with pb frosting on a white plate.

More Chocolate Recipes

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A slice of square chocolate cake topped with a peanut butter frosting and drizzled with melted chocolate.
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Chocolate Cake with Peanut Butter Frosting

This moist chocolate cake is homemade and topped with a creamy peanut butter frosting. It's absolutely delicious!
Prep Time: 25 mins
Cook Time: 28 mins
Total Time: 53 mins
Servings: 20 servings

Ingredients
 

Chocolate Cake

  • 2 1/4 cups all purpose flour
  • 1 1/2 teaspoon baking powder
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon salt
  • 3/4 cup Dutch process cocoa powder - see notes
  • 1 1/2 cups granulated sugar
  • 1/2 cup unsalted butter - softened
  • 1/3 cup vegetable oil
  • 2 teaspoons vanilla extract
  • 1 cup milk - I used 2% but any percentage will be fine
  • 1/2 cup hot water
  • 4 large eggs - at room temperature

Peanut Butter Frosting

Instructions
 

Chocolate Cake

  • Preheat oven to 350°F. Spray a 9×13 inch pan with nonstick cooking spray that contains flour, and set aside.
  • In the bowl of a stand mixer fitted with a paddle attachment, stir the flour, baking powder, baking soda, salt, cocoa powder, and sugar. Add the butter and oil to the dry ingredients and mix on low speed until the mixture resembles sand. 
  • In a large liquid measuring cup whisk the vanilla, milk, and hot water. Pour into the dry ingredients and butter mixture and mix until combined. 
  • Add the eggs, 1 at a time, mixing after each addition. Once fully combined, pour the batter into the prepared baking pan. 
  • Bake for 28-34 minutes or until a toothpick inserted in the center comes out clean. Remove from the oven and set on a wire rack to cool completely.

Peanut Butter Frosting

  • Make the frosting: In the bowl of a stand mixer, or using a hand-held electric mixer, beat the butter and peanut butter until creamy and well combined. With the mixer on low, gradually add the powdered sugar, ½ cup at a time until all of the powdered sugar has been added. Scrape down the sides of the bowl as needed. 
  • Mix in the vanilla, salt, and milk. Turn the mixer to medium-high speed and beat for 30 seconds to 1 minute. 
  • Spread the frosting onto the cooled cake. 
  • Top the cake with mini chocolate chips or melted chocolate drizzled overtop, if desired.

Notes

The butter used in the cake needs to be very soft. If you gently poke your finger into the butter and it leaves a dent, it’s ready to use.
If using unsweetened cocoa powder, the cake will be much lighter in color and won’t have as rich of a chocolate flavor. Read my Best Cocoa Powder for Baking post for more information on the differences of cocoa powders. 
Store the cake covered at room temperature for 2-3 days.
Cake recipe adapted from King Arthur Flour
 

Nutrition

Calories: 545kcal (27%)Carbohydrates: 76g (25%)Protein: 7g (14%)Fat: 26g (40%)Saturated Fat: 14g (70%)Polyunsaturated Fat: 3gMonounsaturated Fat: 8gTrans Fat: 1gCholesterol: 75mg (25%)Sodium: 198mg (8%)Potassium: 215mg (6%)Fiber: 2g (8%)Sugar: 61g (68%)Vitamin A: 500IU (10%)Calcium: 50mg (5%)Iron: 2mg (11%)
Course: Dessert
Cuisine: American
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