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 mixing bowl, combine the graham cracker crumbs, granulated sugar, and melted butter until the mixture resembles wet sand. Press firmly and evenly into the bottom of the prepared pan. Bake for 8 minutes, then set aside to cool slightly.
03 - Using an electric mixer, beat the softened cream cheese and granulated sugar in a large bowl until completely smooth and free of lumps. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract and sour cream until just combined. Do not overmix.
04 - Pour the cheesecake filling over the baked crust, using a spatula to spread it into an even layer.
05 - In a separate bowl, toss the diced peaches with the granulated sugar and lemon juice. Evenly distribute the seasoned peaches over the cheesecake batter and gently press them in so they settle slightly.
06 - Bake for 30 to 32 minutes, or until the edges are set and lightly golden while the center still has a slight jiggle. Avoid overbaking, as the bars will continue to set as they cool.
07 - Allow the cheesecake to cool completely at room temperature, then refrigerate for at least 2 hours until thoroughly chilled and firm.
08 - In a chilled bowl, beat the heavy whipping cream with the powdered sugar using an electric mixer until soft peaks form.
09 - Lift the chilled cheesecake from the pan using the parchment paper overhang. Slice into 12 even bars and top each with a dollop of whipped cream before serving.