01 - Preheat oven to 340°F. Line the bottom of a 9-inch springform pan with parchment paper and grease the sides with butter or cooking spray.
02 - Combine crushed graham crackers, melted butter, chopped pistachios, and sugar in a bowl. Press mixture firmly into the base of the prepared pan. Bake for 10 minutes until lightly golden. Set aside to cool completely.
03 - In a large mixing bowl, beat cream cheese and sugar with an electric mixer until smooth and fluffy, about 2-3 minutes. Scrape down the bowl as needed.
04 - Mix in Greek yogurt (or sour cream) and vanilla extract until fully combined and smooth.
05 - Add eggs one at a time, mixing on low speed just until blended after each addition. Avoid overmixing to prevent cracking.
06 - Fold in ground pistachios and cornstarch until completely incorporated and no dry streaks remain.
07 - Pour filling over the cooled crust. Gently tap the pan on the counter to release any trapped air bubbles.
08 - Bake for 45 minutes until edges are set and firm, but the center still has a slight jiggle when gently shaken. The center will continue to set as it cools.
09 - Turn off the oven, crack the door open slightly, and let cheesecake cool inside for 1 hour. This gentle cooling helps prevent cracks.
10 - Remove from oven and cool to room temperature, about 1 hour. Refrigerate for at least 4 hours or preferably overnight until completely set.
11 - Whip heavy cream with powdered sugar until soft peaks form. Spread or pipe over chilled cheesecake and sprinkle with chopped pistachios just before serving.