Preheat your oven to 350°F (175°C). In a mixing bowl, prepare the Devil’s Food Chocolate Cake mix according to the package instructions.
Pour the batter into a greased 9x13 inch baking pan. Bake for about 30-35 minutes, or until a toothpick inserted comes out clean. Allow to cool completely.
Once the cake is cool, poke holes all over the top using a wooden spoon handle or skewer.
Pour the sweetened condensed milk over the cake, letting it soak into the holes. Allow it to sit for a few minutes.
Drizzle caramel sauce generously over the top of the cake.
Spread Cool Whip over the caramel layer and sprinkle chopped Heath bars on top.
Refrigerate for at least 2 hours before serving.