Allow cake to cool, then poke holes over entire top of cake with the handle of a wooden spoon.
Pour condensed milk over top of cake and let it soak into the holes. Repeat with the butterscotch topping. Pour evenly and allow to soak into the holes.
Refrigerate for at least 4 hours for best results.
Spread whipped topping over the cake making it like frosting. Sprinkle crushed Heath bars over top of cake. Refrigerate for at least one hour. Serve immediately for best results.