01 - Preheat oven to 340°F. Line the bottom of a 9-inch springform pan with parchment paper and grease the sides.
02 - Mix crushed graham crackers, melted butter, chopped pistachios, and sugar in a bowl. Press the mixture into the base of the prepared pan. Bake for 10 minutes. Cool completely.
03 - In a large bowl, beat cream cheese and sugar until smooth and fluffy. Add yogurt or sour cream and vanilla extract, mix until combined.
04 - Add eggs one at a time, mixing gently after each addition to incorporate without overmixing.
05 - Stir in ground pistachios and cornstarch until fully incorporated and smooth.
06 - Pour the filling over the cooled crust. Tap the pan gently to release air bubbles. Bake in the preheated oven for 45 minutes or until edges are set and center still slightly jiggles.
07 - Turn off oven, open door slightly, and let cheesecake cool inside for 1 hour to prevent cracking.
08 - Cool to room temperature, then refrigerate for at least 4 hours, preferably overnight.
09 - Whip heavy cream with powdered sugar to soft peaks. Spread over chilled cheesecake and sprinkle with chopped pistachios before serving.