Mix flour, butter, and sugar. Press into the bottom of a 9x13 in baking pan. Bake at 375°F for 15 min. Let cool.
Cream sugar and cream cheese. Add a little more than half of the Cool Whip. Mix well. Spread on top of 1st layer.
Mix milk and pudding powder. Pour on top of 2nd layer. Refrigerate and allow to set.
Spread remaining Cool Whip over the top of the pudding and sprinkle with chopped pistachios.