Melt butter, and mix flour and nuts together. Press into a 9x13" pan. Bake 15 minutes at 350 degrees. Let cool completely. Soften the cream cheese, add sifted powdered sugar and 1 cup Cool Whip together. Spread on crust when it has completely cooled. Mix pudding mix, milk and vanilla, beat on low speed of mixer until thick, pour over cooled cream cheese mixture. Top with 1 cup Cool Whip mixed with 1/4 cup nuts, very finely chopped. Pour evenly over pudding mixture. Refrigerate each layer as you add it, until well chilled and set.