Pour the heavy cream into medium sized mixing bowl.
To that, add the pistachio pudding mix.
With a hand mixer, start mixing slowly at first (so you don't get pudding mix powder everywhere) and then once the two ingredients are combined, beat until you get a light and fluffy pudding mixture.
Then, gently fold the Cool Whip into the pudding mixture, until no white streaks are showing.
Add the pistachio pie filling into the graham cracker crust and garnish as you choose.
