This peanut butter chocolate cake is a rich homemade chocolate cake paired with a creamy peanut butter frosting and topped with a chocolate ganache drip and peanut butter cups.
Preheat the oven to 350 degrees F. Grease 4 8-inch round cake pans with nonstick cooking spray. Place an 8-inch parchment paper round in the bottom of the cake pan and spray the top of the paper with nonstick cooking spray.
In a medium mixing bowl, add the 2 cups all-purpose flour, 1 cup unsweetened cocoa powder, 1 teaspoon baking soda, 1 teaspoon baking soda, and 1 teaspoon salt. Whisk until combined. Set aside.
In a large mixing bowl, add the melted ½ cup butter, 3/4 cup vegetable oil, and 2 cups granulated sugar. Using a hand mixer on medium speed, beat until smooth and fluffy, about 1 to 2 minutes.
Add the 2 teaspoons vanilla extract and 4 large eggs, one at a time. Beat until each egg is combined. Scrape down the sides and bottom of the bowl.
Alternate adding the dry ingredients and 2 cups whole milk starting and ending with the dry ingredients. Beat on medium speed until each addition is combined and scrape down the sides of the bowl.
Divide the batter evenly into the prepared cake pans and spread evenly to the edges using an angled spatula.
Place in the preheated oven and bake for 20-25 minutes or until a toothpick inserted in the center of each cake comes out clean or with moist crumbs. Wet batter means you need to bake the cake longer.
Allow the cakes to cool for 20 minutes before turning out onto a wire rack to cool completely.
While the cakes are cooling, make the peanut butter frosting.
Peanut Butter Frosting
In a large mixing bowl, add the 1 ½ cups butter, 2 1/4 cups peanut butter, and 2 teaspoon vanilla extract. Beat using the hand mixer on medium speed until smooth and combined.
Add the 6 cups powdered sugar and 4 - 6 tablespoons heavy whipping cream. Beat on low speed until the powdered sugar is mostly worked in. Turn the hand mixer to medium speed and continue to beat until the powdered sugar is well incorporated and the frosting is fluffy.
Chocolate Ganache
Add the 1 cup milk chocolate chips and ⅓ cup heavy whipping cream to a small microwave-safe bowl. Microwave in 30-second increments and stir after each increment until the ganache is smooth and combined.
Allow the ganache to cool for at least 15 to 20 minutes before using.
Assemble Cake
Use a large serrated knife or cake leveler to level the cakes.
Place the first layer of cake on a cake plate and add a large scoop of frosting to the top. Using an angled spatula, evenly spread the frosting to the edges of the cake.
Repeat adding a layer of cake and frosting, making sure the cake stays level after each layer.
Add the remaining frosting on the top of the cake and begin evenly spreading it out and down the sides the cake with a large angled spatula until the cake is completely covered.
Pour the ganache over the top of the cake and spread into an even layer, allow some ganache to drip down the sides. You can use a squeeze bottle or piping bag to get a cleaner drip. If desired, you can decorate with extra frosting and reese’s peanut butter cups. Slice and enjoy!