Preheat oven according to cake mix package directions.

Combine cake mix and cocoa in large mixing bowl. Prepare and bake according to cake mix package directions. Cool completely. (I do this over a wine bottle)

Place a plate over the Bundt pan and invert cake. (You may need to use a knife around the edges to help loosen cake.)

Sprinkle with confectioner's sugar or serve topped with fresh strawberries and whipped cream.