Preheat oven to 350. Make chocolate cake according to package directions and put in a greased 9 x 13 pan. Bake until done. While cake is still hot, poke holes all over it with a fork. Pour the entire can of condensed milk over the cake. Then pour the entire jar of caramel sauce over the cake. Let cool. When the cake is cool, frost with Cool Whip. Sprinkle the chopped snickers over the top. Store in fridge.