Is there any better combination of flavors than peanut butter and chocolate? We don’t think so, and that’s why this luscious dark chocolate cake with rich peanut buttery buttercream frosting was a huge hit in our household.
Preheat oven to 350°F. Grease two 8" round pans and line the bottoms with parchment paper, then grease the paper.
In a medium mixing bowl, sift or whisk together the flour, baking soda, and salt.
In a large mixing bowl, cream the shortening and sugar until smooth. Beat in the eggs and the extra yolks until the mixture is smooth and fluffy, then stir in the vanilla extract. In a separate bowl, combine the melted butter and the cocoa powder until the mixture is smooth, then add to the batter.
Add the flour and the milk alternately in 3 or 4 portions, beating until the mixture is well blended between each addition.
Divide batter evenly between the two pans. Bake 25-30 minutes, or until a toothpick inserted into the center comes out clean. Because ovens can be weird with cooking times, you may want to check your cakes a couple of minutes before the 25 minutes is up, to better gauge your cake's progress.
Cool the cakes in the pans for 5 minutes, turn out onto cooling racks and remove the paper, then invert the cakes so the paper side is on the bottom once again. Allow the cakes to cool completely before frosting.
Combine the butter and peanut butter in a large mixer bowl and mix until well combined.
Add about half of the powdered sugar and mix until smooth.
Add 3 tablespoons of milk and mix until smooth.
Add remaining powdered sugar, a half cup at a time, mixing between each addition until the frosting smooths out again.
Gradually add remaining milk and mix until smooth, keeping an eye on the consistency of the frosting so it doesn’t get too thin.
You may want to make the frosting before starting the cake. Put the buttercream in the fridge to firm up while you let the cake cool completely, and take it out about 15 minutes before you start assembling the cake. This way, the frosting is still soft enough to easily spread, but will also hold its shape if you're piping with it.
Peanut Buttery Buttercream (and the style of this cake in general) heavily inspired by the one used in Life, Love, and Sugar's recipe for a peanut butter chocolate layer cake. The Beard wanted a chocolate and peanut butter cake.