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 granulated sugar in a bowl. Press the mixture firmly into the base of the prepared pan, creating an even layer.
03 - Bake the crust for 10 minutes until set and lightly golden. Remove from oven and let cool completely while preparing the filling.
04 - In a large bowl, beat cream cheese and sugar with an electric mixer until smooth and fluffy, about 2-3 minutes. Scrape down the sides of the bowl as needed.
05 - Mix in Greek yogurt (or sour cream) and vanilla extract until fully incorporated and smooth.
06 - Add eggs one at a time, mixing on low speed after each addition just until blended. Avoid overmixing to prevent cracking.
07 - Fold in ground pistachios and cornstarch until evenly distributed throughout the batter.
08 - Pour the filling over the cooled crust. Tap the pan gently on the counter to release air bubbles. Bake for 45 minutes until edges are set but center still jiggles slightly.
09 - Turn off the oven and crack the door open slightly. Let cheesecake cool inside for 1 hour to prevent cracking from rapid temperature change.
10 - Remove from oven and cool to room temperature, then refrigerate for at least 4 hours or preferably overnight until fully set.
11 - Whip heavy cream with powdered sugar until soft peaks form. Spread over the chilled cheesecake and sprinkle with chopped pistachios before serving.