First layer: melt butter. Add flour and 1 cup pecans. Press in bottom of pan 9 x 13. Bake at 375 degrees for 15 minutes.
Second layer: Cream together cream cheese, powdered sugar, 1 cup Cool Whip. Mix well. Spread over first layer.
Third layer: Mix 2 packages pudding. Mix with milk. Blend 2 minutes and spread over second layer.
Fourth Layer: spread rest of Cool Whip on top. Sprinkle with pecans and chill several hours.