Preheat your oven to 325°F (160°C).
In a mixing bowl, combine the graham cracker crumbs, melted butter, and sugar for the crust. Mix until combined.
Press the mixture firmly into the bottom of a 9-inch springform pan. Bake in the preheated oven for 10 minutes. Remove from oven and set aside to cool.
In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy.
Gradually add the granulated sugar and mix until well combined.
Add the eggs one at a time, mixing well after each addition. Then, add the vanilla extract and mix again.
Mix in the sour cream and pistachio paste until the filling is smooth and well incorporated.
Fold in the heavy cream using a rubber spatula until combined. Be careful not to overmix.
Pour the cheesecake filling into the cooled crust.
Bake in the oven for about 50-60 minutes, or until the edges are set and the center is slightly jiggly.
Turn off the oven and let the cheesecake cool inside for about an hour. This helps to prevent cracking.
After cooling, remove the cheesecake from the oven and let it cool completely at room temperature.
Once cooled, cover the cheesecake and refrigerate for at least 4 hours (or overnight) to fully set.
When ready to serve, top with whipped cream and sprinkle with chopped roasted pistachios for garnish, if desired.