Step 1

Preheat oven to 350 (or whatever temp it says on the cake box)

Step 2

In a large bowl, combine all the ingredients for the cake plus vanilla extract and cornstarch. Bake according to package directions in a 9×13 baking pan.

Step 3

Poke holes into the top of the cake using the end of a wooden spoon or a large meat fork.

Step 4

In a small bowl, combine about 3/4 of the ice cream topping (save the other 1/4 for later) with sweetened condensed milk. Mix well.

Step 5

Pour over the top of the cake, spreading if necessary to cover the whole cake. Then, spread Cool Whip on top.

Step 6

Sprinkle with chopped Heath bars and drizzle with remaining ice cream topping. Chill until serving.