Combine the cake mix, pudding mix, oil, eggs, cocoa, buttermilk, and food coloring; beat for 4 minutes on medium speed, scraping the sides and bottom of the bowl several times. Distribute the batter among cupcake liners, filling about ½-¾ full. Bake at 350° for 15-20 minutes or until the cakes spring back when gently pressed on. Let cool and frost with your favorite cream cheese icing.