Crush oreos in a blender, mix in melted butter, and press into a 9x13 pan. Combine the peanut butter, powdered sugar and cream cheese until smooth, fold in 1/2 of the cool whip. Spread over the oreo crust. Whisk the chocolate pudding mix into the 2 cups of milk. Evenly spread over the peanut butter cream cheese layer.
Spread the remaining Cool Whip over top then sprinkle with the chopped Butterfinger candy bars.
Cover with plastic wrap and refrigerate for at least 1 hour before serving.