Preheat your oven to 350 degrees Fahrenheit and lightly grease a 9x13 inch cake pan.

Prepare and bake the cake mix according to the package directions. Allow it to cool after baking.

Once cooled, use a fork or the back of a wooden spoon to poke holes in the cake. Be careful not to poke all the way to the bottom.

Pour the sweetened condensed milk evenly over the top of the cake, letting it seep into the holes.

Drizzle the caramel syrup over the cake as well, distributing it evenly to enhance the flavor.

Refrigerate the cake for at least 2 hours, allowing the flavors to meld together.

Just before serving, remove the cake from the refrigerator. Spread the thawed cool whip over the entire surface of the cake.

Finally, sprinkle the crushed Heath candy bars generously on top and enjoy!