01 - Preheat 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 graham cracker crumbs, 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 sugar in a large bowl on medium speed until completely smooth and free of lumps. Add the eggs one at a time, beating well after each addition. Blend in the vanilla extract and sour cream until just incorporated. Avoid overmixing to prevent excess air in the batter.
04 - Pour the cheesecake filling over the partially baked crust, using a spatula to spread it into an even, level layer.
05 - In a separate bowl, toss the diced peaches with sugar and lemon juice until coated. Distribute the peaches evenly over the cheesecake batter and gently press them in. Bake for 30 to 32 minutes, until the edges are set and lightly golden while the center retains a slight jiggle.
06 - Allow the cheesecake to cool completely at room temperature, then refrigerate for at least 2 hours until thoroughly chilled and firm.
07 - In a chilled bowl, beat the heavy whipping cream with powdered sugar using an electric mixer until soft peaks form.
08 - Lift the chilled cheesecake from the pan using the parchment overhang. Slice into 12 even bars and top each bar with a dollop of whipped cream before serving.