Combine flour, butter and 1 cup nuts. Press into a 13x9 inch greased pan.
Bake 20 minutes. Cool.
For the Cheesecake Layer
Beat cream cheese and powdered sugar together. Stir in one tub of the whipped topping. Spoon over crust.
For the Pistachio Layer
Beat pudding and milk for 1-2 minutes or until thickened.
Pour over cheesecake layer.
Chill for at least 2 hours.
Spread the remaining tub of whipped topping over the top of the pistachio layer.
Sprinkle with remaining walnuts.
Chill for 1-2 hours.
Cut into squares and serve cold.
Notes
Even Crust Thickness: When pressing the crust into the pan, aim for an even thickness throughout. This ensures that the crust bakes uniformly and provides a sturdy base for the layers above. Using the bottom of a flat measuring cup can help to compact the crust evenly.
Thickening the Pistachio Layer: To ensure a creamy and thick pistachio layer, beat the pudding mix with the milk for the full 1-2 minutes as directed. This allows the pudding to fully thicken before pouring it over the cheesecake layer, resulting in a more stable and decadent filling.
Proper Chilling Time: For best results, chill the pistachio pie bars for the recommended times. Allowing the dessert to chill for at least 2 hours after assembling ensures that the layers set properly and develop their flavors. Additionally, chilling the bars for another 1-2 hours after adding the final whipped topping layer allows the dessert to firm up, making it easier to slice into neat squares for serving.