01 - Preheat the oven to 350°F. Line a 9×9-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
02 - In a medium bowl, combine the graham cracker crumbs, granulated sugar, and melted butter, stirring until the mixture resembles wet sand. Press the crumb mixture firmly and evenly into the bottom of the prepared pan. Bake for 8 to 10 minutes until lightly golden. Set aside to cool slightly.
03 - Using an electric mixer, beat the softened cream cheese and granulated sugar on medium speed until completely smooth and free of lumps. Add the eggs one at a time, mixing well after each addition. Blend in the vanilla extract and sour cream until fully incorporated.
04 - In a separate bowl, toss the diced peaches with granulated sugar, lemon juice, and cornstarch until evenly coated. Spread the peach mixture in a uniform layer over the cheesecake batter.
05 - Pour the cheesecake filling over the partially cooled crust, spreading it into an even layer. Bake for 30 to 35 minutes, or until the center is set with only a slight jiggle remaining. Remove from the oven and allow to cool to room temperature.
06 - Refrigerate the cheesecake bars for at least 3 hours, or until thoroughly chilled and firm. Use the parchment overhang to lift the slab from the pan, then cut into 12 even bars using a sharp knife.
07 - In a chilled bowl, whip the heavy cream with powdered sugar until soft peaks form. Drizzle or pipe over the sliced bars just before serving.