01 - Preheat oven to 340°F. Line the bottom of a 9-inch springform pan with parchment paper and grease the sides thoroughly.
02 - Combine crushed graham crackers, melted butter, chopped pistachios, and sugar in a bowl. Press the mixture firmly into the base of the prepared pan. Bake for 10 minutes, then allow to cool completely.
03 - In a large bowl, beat cream cheese and sugar until smooth and fluffy. Add yogurt or sour cream along with vanilla extract, mixing until fully incorporated.
04 - Add eggs one at a time, mixing gently after each addition just until combined. Avoid overmixing to prevent air bubbles.
05 - Fold in ground pistachios and cornstarch until completely integrated into the batter.
06 - Pour the filling over the cooled crust. Tap the pan gently on the counter to release any trapped air bubbles. Bake for 45 minutes or until edges are set while the center retains a slight jiggle.
07 - Turn off the oven and crack the door open slightly. Let the cheesecake cool inside for 1 hour to prevent cracking.
08 - Remove from oven and cool to room temperature. Refrigerate for at least 4 hours, preferably overnight, for optimal texture.
09 - Whip heavy cream with powdered sugar until soft peaks form. Spread generously over the chilled cheesecake and garnish with chopped pistachios immediately before serving.