Make bottom crust by cutting butter into flour and chopped nuts. Press mixture into the bottom of a 13"x9" pan. (I use a glass pan.) Bake in 350 degree oven for 15 minutes. Cool.
Mix the powdered sugar, cream cheese and Cool Whip together and spread on cooled crust. Put in refrigerator for 15 minutes. Add a layer of sliced bananas on top of chilled filling.
Mix the 2 packages of vanilla pudding with the 4 cups milk. Pour on top of bananas and filling. Top with Cool Whip and sprinkle with chopped nuts. Keep refrigerated until ready to serve.