Bake cake in a 9 by 13 inch pan and let cool.Crumble the cake into small pieces.Set aside.
Mix melted butter,sugar and cream cheese together and fold intoCool Whip.
Using a heavy spoon or meat mallet,crush the butterfinger bars into little pieces after placing them in azip lock bag.
In a trifle bowl layer one half of the cake pieces on the bottom.Spoon one half of the cream mixture on top of the cake.Top off the cream mixture with one half of the crushed Buttrfinger candy bars.Repeat with the rest of the ingredients,ending with the candy bars.
Drizzle some chocolate syrup over the top.
Make this a couple hours before you serve it.Refrigerate.