Gooey Chocolate Caramel Cake Recipe

Preheat oven to 350°. Grease and lightly flour 13x9x2 baking pan; set aside. Prepare cake mix according to package directions. Pour into prepared pan. Bake according to package directions. Cool in pan on wire rack. Using handle of wooden spoon, poke holes about 1" apart over top of cake. Pour sweetened condensed milk, then caramel topping over cake. Spread evenly with Cool Whip. Before serving, sprinkle with chopped Heath bars. Store cake in refrigerator.