Found this recipe several years ago but I forgot where it came from. I do know one thing it is OFF THE CHAIN! This cake is soooooooo moist and flavorful you will want to eat the WHOLE cake at once. Try it you'll like it!
Preheat oven 350. Grease and flour or baking spray two 9-inch round cake pans, set aside. In large bowl mix the cake mix, chocolate milk, butter, eggs, sour cream, and dry pudding mix with electric mixer until smooth (batter will be thick). Stir in chocolate chips with a large spoon.
Spoon batter into prepared pans. Bake for 33 minutes but do test for doneness. Remove from oven and cool on baking rack for 10 minutes before removing from pan. Cool completely before frosting.
In medium bowl mix melted butter, cocoa, powdered sugar, vanilla and milk. Beat to spreading consistancy. Add small amounts of additional milk if needed.