Preheat oven and prepare cake mix according to package directions. Line two 9-inch round pans with parchment paper or spray thoroughly with cooking spray. The only way you can mess up this cake is if your cake sticks to the pans so make sure that doesn't happen. Bake cake according to package directions; until golden brown and center passes the toothpick test. Once done, let cakes cool and invert on a wire rack to cool further.
Beat 1 cup of milk and pudding mix with a whisk or mixer for 2 minutes. Gently fold in whipped cream. Let stand 5 minutes. Stack cake layers on serving plate, spreading pudding mixture between layers.
For the glaze: Microwave chocolate and butter on high for one minute in a small microwave safe bowl. Stir until chocolate is melted. Add powdered sugar and 2 tablespoons milk; mix well until smooth. Spread over the top of the cake immediately letting drip down the sides. Refrigerate at least one hour before serving.