8tablespoonsunsalted buttervery soft (113g or 4oz)
1cupgranulated sugardivided (222g)
¾cupbrown sugarpacked (170g)
For the peanut butter frosting:
1cupunsalted buttersoftened (226g or 8oz)
1cupsmooth peanut butterlike Jiff or Peter Pan (260g)
2 ½cupspowdered sugar(287g)
⅛teaspoonsalt
1teaspoonvanilla extract
1tablespoonheavy creamor milk as needed (+-) for desired consistency
For the chocolate ganache (optional):
⅓cupheavy cream
1 ½tablespoonscorn syrup
3ouncessemisweet chocolate choppedor bittersweet
chopped dry-roasted salted peanuts for garnish
Instructions
To prepare the cake:
Preheat oven to 350°F. Adjust the oven rack to the middle position. Butter two 9-inch round cake pans with 2-inch high sides. Dust pans with flour and knock out any excess. Set aside.
In a medium heatproof bowl combine the unsweetened chocolate, cocoa and hot water. Set the bowl over a saucepan with 1-inch of simmering water. Do not let the bowl touch the water. Stir with a spatula until completely melted, about 3 minutes. Add ½ cup of granulated sugar and stir until the mixture is thick and glossy. Remove from the hot water and set aside to cool.
In a separate medium bowl whisk together the flour, baking soda and salt; set aside. In a 2-cup measuring cup with a spout whisk together the buttermilk, vegetable oil and vanilla; set aside.
In the bowl of a stand mixer fitted with the whisk attachment, whisk the eggs and medium-low speed until combined. Add the remaining ½ cup of granulated sugar and all the brown sugar. Turn the mixer speed to high and whisk until the mixture is thickened, lighter in color and fluffy, about 3 to 4 minutes.
Replace the whisk with the paddle attachment. Add the cool chocolate mixture and blend until incorporated scraping down the sides and bottom of the bowl as needed with a rubber spatula. Add the softened butter one tablespoon at a time mixing well after each addition before adding the next.
Next add one-third of the flour mixture then half the buttermilk blending well after each addition. Repeat adding half the remaining flour, then all remaining buttermilk and finally add the last of the flour mixture. Scrape down the sides and bottom of the bowl and fold a few times with a spatula to ensure all flour is incorporated. Divide the batter evenly between the prepared cake pans.
Bake the cakes until a toothpick inserted in the center comes out with no wet batter, about 28 to 35 minutes. Don’t over-bake! Moist crumbs are good. Cool the cakes in the pans for 15 minutes then invert onto a wire cooling rack. Cool completely before icing.
To prepare the peanut butter frosting:
Beat the butter and peanut butter together until smooth. Sift in the powdered sugar and salt. Blend on low until combined. Scrape down the sides and bottom of the bowl and add the vanilla. Beat on medium until incorporated then increase the speed to medium-high. Beat until light and fluffy, about 3 to 5 minutes. Add a tablespoon of cream as needed for desired consistency.
Place one layer of cooled cake on a cake stand or serving platter. Spread 1 ½ cups of frosting over the cake layer. Top with the remaining cake round. Spread frosting on the sides and top of the cake. Refrigerate while preparing the ganache, if using.
To prepare the chocolate ganache:
Heat the cream and corn syrup in a small saucepan over medium heat until it comes to a simmer. Remove from the heat and add the chopped chocolate. Stir and cover with a lid. Set aside for 5 minutes. Whisk gently until smooth.
Spread the ganache on top of the cake allowing any extra to decoratively drip down the sides. Sprinkle the ganache with chopped peanuts. Refrigerate to help set the ganache or leave out at room temperature for an hour or until ready to serve.
Notes
Store cake covered at room temperature for up to 3 days or refrigerate for longer storage. Allow to come to room temperature before serving.
Frosting recipe adapted from Cook’s Illustrated
Nutritional information is calculated using an ingredient database and should be considered as an estimate. When multiple ingredient alternatives are given, the first listed is calculated for nutrition. Garnishes and optional ingredients are not included.