1-Preheat oven to 350 degrees and lightly: Preheat oven to 350 degrees and lightly grease a 9×13 cake pan.
2-Prepare and bake cake mix according to: Prepare and bake cake mix according to package directions.
3-Remove cake from the oven and allow: Remove cake from the oven and allow to cool. Using a fork or the back of a wooden spoon, poke holes in cake. *Be sure not to poke holes all the way to the bottom*
4-Pour sweetened condensed milk and caramel syrup: Pour sweetened condensed milk and caramel syrup evenly over top of cake allowing it to seep down into the holes.
5-Refrigerate cake for at least 2 hours: Refrigerate cake for at least 2 hours.
6-When you are ready to serve cake,: When you are ready to serve cake, remove from the fridge. Spread cool whip over cake and sprinkle crushed heath bars evenly on top of cake. Enjoy!