1Preheat the oven to 350 degrees F. Butter 9x13 cake pan.
Sift together flour, sugar, baking powder and soda; set aside. Cream together butter, eggs, vanilla, sour cream and cocoa; whisk into flour mixture until well blended. Pour batter prepared cake pan.
Bake 30 to 35 minutes or until toothpick inserted in center comes out clean.
As soon as cake is removed from the oven poke holes all over top of cake with a wooden spoon handle. Blend together caramel topping and sweetened condensed milk; pour over cake. Crush 2 Butterfingers and sprinkle over cake. Chill cake for 2 hours at least or over night.
Stir together cream cheese and Cool Whip until well blended. Spread over cake. Crush remaining candy bars and sprinkle over cake.