1. In a medium bowl, stir together the graham cracker crumbs, melted butter, and granulated sugar until the mixture looks like wet sand. Press it firmly into the bottom of a 9-inch springform pan. Chill the crust while you prepare the filling.

2. In a large mixing bowl, beat the softened cream cheese until smooth and creamy. Add the powdered sugar, pistachio pudding mix, and vanilla extract, then mix until fully combined and fluffy.

3. In a separate bowl, whip the cold heavy whipping cream until stiff peaks form.

4. Gently fold the whipped cream into the pistachio cream cheese mixture until no streaks remain. Fold in the chopped pistachios.

5. Spoon the filling over the chilled crust and smooth the top evenly with a spatula.

6. Cover and refrigerate for at least 6 hours, or overnight, until fully set.

7. Before serving, top with whipped topping and extra chopped pistachios if desired. Slice and serve chilled.