Use either a choclate or German chocolate cake and bake as directed on mix box in 9X13 inch pan. While still warm, poke holes all over the top with the end of a wooden spool handle. Pour a can of condensed milk over the cake. Immediately pour a small jar of carmel ice cream topping over the cake. Let cool. Cover with thawed cool whip and sprinkle broken Heath candy bar crumbs over top. Refrigerate.