¼cupDutch processed cocoa powderI used Droste brand
Instructions
For the cake
Preheat oven to 350°F. Line two 8-inch round cake pans with parchment paper, spraying with non-stick cooking spray before and after placing parchment. Set aside. (If you prefer cupcakes, line muffin pans with 24 cupcake liners.)
In a medium bowl, whisk together the cake flour, ¼ cup cocoa powder, baking soda and salt. Set aside.
In a large bowl, cream butter. Add sugar, eggs, beat 5 minutes. Add melted chocolate and vanilla. Stir in dry ingredients alternately with sour cream. Stir in the boiling water, mixing thoroughly. Pour into prepared pans. Bake for 40-45 minutes or until a toothpick inserted in middle comes out clean. Cool in pans 10 minutes. (If making cupcakes, bake for 21-23 minutes or until a toothpick inserted in center comes out clean.)
For the frosting
Melt chocolate in the microwave on high for 45 seconds. Stir until smooth. Mix in softened butter. Set aside Combine cocoa, powdered sugar, milk and vanilla extract in a bowl. Stir in the chocolate mixture. Set the bowl on ice and beat until thick enough to spread. Spread cooled cake layers with a wooden spoon or an offset spatula. Serve and enjoy.
For cupcakes
If you prefer to make cupcakes, follow the instructions for the cake and pour batter into muffin pans lined with cupcake liners. The recipe will make 30 cupcakes.
Video
Notes
Make the icing AFTER the cake layers are cooled. This is because once you make the frosting, you will want to use it immediately (while it's still chilled since you will be beating it over a bowl of ice).