Mix flour and melted butter with a beater. Pack on bottom of 13 x 9 inch pan.
Bake at 350 degrees about 20 minutes.
Let cool. Beat cream cheese and powdered sugar. Blend in 1 cup whipped topping. Smooth mixture over cooled pastry.Beat instant pudding with milk until thick.
Spread over cheese layer. Top with remaining whipped topping.
Sprinkle with chopped nuts. Refrigerate overnight or at least 3 hours. When ready to serve, cut into 24 bars.