Make the Pistachio Crust:
In a small to medium mixing bowl, combine the graham cracker crumbs, granulated sugar, and chopped pistachios. Mix well.
Add the melted butter and stir until the crumbs are fully coated.
Transfer the mixture to a 9-inch cake pan, pressing it evenly into the base.
Bake at 180°C (350°F) for 5-8 minutes, watching carefully to avoid burning. Let the crust cool to room temperature.

Prepare the Cheesecake Filling:
Lower the oven temperature to 140°C (280°F).
In a large mixing bowl, beat together the room-temperature cream cheese, granulated sugar, sour cream, heavy cream, kosher salt, and vanilla extract until smooth and creamy using an electric hand mixer.
Add the pistachio paste and mix until well combined.
Sift the cornstarch into the mixture and mix until there are no lumps.
Whisk the eggs with a fork and gradually add them to the mixture, mixing until smooth and creamy.
Pour the cheesecake batter over the prepared crust, tapping the pan gently on the counter to release air bubbles.

Bake the Cheesecake:
Bake the cheesecake in the preheated oven for about 1 hour, or until the edges are set and the center is slightly jiggly.
Open the oven door halfway and let the cheesecake cool to room temperature for 1-2 hours.

Chill the Cheesecake:
Once cooled, wrap the cheesecake tightly in plastic wrap and refrigerate for at least 5 hours (overnight for best results).

Make the Pistachio Topping:
In a medium mixing bowl, combine the chopped white chocolate, pistachio paste, and heavy cream.
Microwave in 30-second pulses, stirring in between, until the mixture is smooth and creamy.
Stir in the chopped pistachios.

Assemble and Serve:
Run a thin knife around the edges of the cheesecake to loosen it from the pan. Carefully release the springform pan.
Spread the pistachio topping over the cheesecake evenly using a spoon or offset spatula.
Slice and serve, enjoying the rich, nutty flavor of this delicious dessert!