Prepare cake mix according to package directions. Put into 9 X 13 inch greased and floured baking dish.
Bake at 350 degrees for 35 to 38 minutes.
While cake is still warm, poke holes in top of cake with the end of a wooden spoon.
Pour sweetened condensed milk over top.
Let cake cool.
Pour hot fudge topping over top of cake and let set.
Spread on whipped topping and garnish with crushed Heath bars.
Not a NESTLÉ®-tested recipe.