01 - Preheat oven to 350°F. Line a 9x9-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
02 - In a bowl, combine graham cracker crumbs, sugar, and melted butter until evenly moistened. Press the mixture firmly into the bottom of the prepared pan. Bake for 8 to 10 minutes until lightly golden. Set aside to cool slightly.
03 - In a large bowl, beat cream cheese and sugar with an electric mixer until smooth and creamy. Add eggs one at a time, mixing well after each addition. Blend in vanilla extract and sour cream until fully incorporated. Pour the batter evenly over the cooled crust.
04 - Toss diced peaches with sugar, lemon juice, and cornstarch until coated. Spread the peach mixture in an even layer over the cheesecake batter.
05 - Bake for 30 to 35 minutes, or until the center is set with only a slight jiggle. Remove from the oven and allow to cool completely at room temperature.
06 - Refrigerate for at least 3 hours, or until fully chilled and firm. Use the parchment overhang to lift the dessert from the pan, then cut into 12 even bars.
07 - In a chilled bowl, whip heavy cream with powdered sugar until soft peaks form. Drizzle or pipe over the bars before serving.