Toffee Butterscotch Cake

To a medium bowl, add the butterscotch topping, sweetened condensed milk, whisk to combine, and slowly and evenly pour over the surface of the cake. Run a spatula back and forth as necessary over the surface of the cake to encourage the mixture to sink down into the holes.
Cover cake and place it in the fridge for at least 2 hours, or until chilled. For a make-ahead option, note that the cake will keep in the fridge for a couple of days before serving it.
Before serving, evenly spread the whipped topping over the cake, evenly sprinkle with the toffee bits, and serve.