1 box (2-layer size) chocolate cake mix
1 brick (8-oz) cream cheese, softened
3 cups powdered sugar
1 stick butter, softened
1 carton frozen whipped topping, thawed
1 can chocolate frosting
2 tbsp milk
Prepare and bake cake mix according to the package directions. Remove from oven and let stand for 10 minutes. Turn cake out onto a wire rack.
When cake is cooled, cut in half lengthwise; return bottom half to the pan.
To make the filling, combine the cream cheese, powdered sugar, and butter using an electric mixer until blended and smooth. Fold in the whipped topping. Spread the mixture over the bottom layer in the pan; top with the top half of the cake.
Stir the milk into the chocolate frosting for easier spreading. Spread over the top of the cake.
Keep cake in the refrigerator.