Preheat the oven to 350° and in a large bowl prepare the cake mix accordingly to the back of the box.
Spray a 9x13 baking dish with non-stick cooking spray. Once the batter is made, pour into the prepared pan and place in the preheated oven.
Bake for 25-30 minutes. Let the cake cool completely.
Using a skewer, or the end of a wooden spoon, poke holes all around the top of the cake, making sure to go halfway/ all the way down.
In a medium sized bowl add the condensed milk, caramel sauce, peanut butter, powdered sugar, vanilla extract and the chopped butterfingers and stir until well combined.
Pour the mixture all over top of the cake and making sure to spread into the holes as well and all over.
Cover the cake and place in the refrigerator for 1-2 hours.
Once it has chilled add the whipped topping all over top of the cake evenly.
Sprinkle the 1/2 cup of butter fingers all over top of the whipped cream. Slice and enjoy