Preheat oven to 325°F (160°C).,Mix graham cracker crumbs, sugar, and melted butter. Press into the bottom of a 9-inch springform pan. Bake for 8–10 minutes. Let cool.,In a large bowl, beat cream cheese until smooth. Add sugar and beat until well combined.,Add eggs one at a time, beating well after each.,Mix in pistachio paste, vanilla, and cream or sour cream until smooth.,Pour the filling over the cooled crust. Smooth the top.,Place the pan in a water bath and bake for 50–60 minutes, until the edges are set but the center still jiggles slightly.,Turn off the oven and let cheesecake cool inside with the door ajar for 1 hour.,Refrigerate for at least 4 hours or overnight.,Garnish with chopped pistachios before serving.