01 - Preheat oven to 350°F. Line a 9x9-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
02 - In a medium bowl, combine 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 softened cream cheese and sugar together in a large bowl until completely smooth and free of lumps. Add eggs one at a time, beating well after each addition. Stir in vanilla extract and sour cream until just combined — do not overmix.
04 - Pour the cheesecake filling over the cooled crust, spreading it into an even layer with a spatula.
05 - In a separate bowl, toss the diced peaches with granulated sugar and lemon juice until coated. Distribute the peach pieces evenly across the cheesecake surface, gently pressing them down into the batter.
06 - Bake for 30–32 minutes, or until the edges are set and lightly golden while the center still has a slight jiggle. Avoid overbaking.
07 - Allow the cheesecake to cool completely at room temperature, then refrigerate for a minimum of 2 hours until thoroughly chilled and firm.
08 - Beat heavy whipping cream with powdered sugar using an electric mixer until soft peaks form. Keep refrigerated until ready to serve.
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.