Mix milk and pudding together. Then fold in the cool whip and blend well. Using a 9 X 13 pan, place a single layer of graham crackers on the bottom of the pan. Pour 1/2 of the pudding mixture on top. Place a second layer of graham crackers over this and pour the rest of the pudding mixture over that. Place a third layer of graham crackers over the mixture and frost this layer with the chocolate frosting.
Refrigerate overnight to allow the graham crackers to soften.