Bake the Cake: Begin by following the instructions on the chocolate cake mix box to prepare the batter. Pour this mixture into a round cake pan (or divide it between two pans if you have them available). Bake until a toothpick inserted into the center emerges clean. Once baked, allow the cake to rest in the pan for approximately 10 minutes to help it set.

Cool and Slice: After the resting period, carefully invert the cake onto a cooling rack to let it cool completely. When fully cooled, cut the cake horizontally into two layers. If you opted for two separate pans, this step can be skipped.

Prepare the Cream Filling: In a mixing bowl, combine the softened cream cheese and margarine until the mixture is smooth and well blended. Gradually incorporate the powdered sugar, mixing until fluffy and uniform. Gently fold in the thawed Cool Whip until fully integrated. This filling should be light, creamy, and incredibly inviting.

Layer the Cake: Place the bottom half of the cake back into the cake pan. Spread the prepared cream cheese filling evenly over this layer, ensuring it reaches the edges. Carefully position the other layer of cake on top.

Frost the Cake: For the finishing touch, take the can of chocolate frosting and mix in the 2 tablespoons of milk to achieve a smoother consistency. Generously apply the frosting over the top layer of the cake, ensuring it is thoroughly covered.

Chill and Serve: Transfer the cake to the refrigerator, allowing it to chill for at least one hour. This cooling period enhances the texture and flavor, making each slice even more enjoyable.