In a large bowl, add the graham cracker crumbs, sugar, and melted butter. Mix until well combined.
Press into a 8 x 8-inch pan.
Bake for 7-8 minutes.
Remove from oven and cool completely.
In a large bowl mix, the milk and pudding mix for 1-2 minutes until the pudding begins to thicken.set aside
Cream Cheese Layer:
Beat cream cheese, powdered sugar and the 1 cup of whipped topping. Mix until smooth and creamy.
Spread half of the pudding onto the cooled crust. Then the whole cream cheese mixture, and then the rest of the pudding. You can add another optional layer of just whipped topping (if desired)
Chill for about 2-3 hours
Pistachio Pudding Icebox Cake actually holds up quite well in the freezer. You have a couple of options:
Freeze the cake whole. Wrap the container with plastic wrap or place into a large freezer bag. (I recommend using a disposable pan if this is your plan). To defrost, unwrap the pan and thaw in the refrigerator.
Freeze individual slices. Slice the cake into squares, place slices on a cookie sheet and freeze for about 30 minutes so they firm up. Then wrap each individual square in plastic wrap and place into a large freezer bag. Thaw in the refrigerator.