Lightly grease a 9x13-inch baking pan. In a bowl, combine graham cracker crumbs, granulated sugar, and melted butter until well blended. Press evenly into the prepared pan. Refrigerate for 30 minutes or bake at 375°F for 8 minutes until golden. Let cool completely before adding filling.

In a saucepan over medium heat, mix sugar and cornstarch, then gradually add 2 cups of water, stirring continuously. Bring to a boil and thicken for 1-2 minutes. Remove from heat and stir in peach Jello until dissolved. Fold in sliced peaches and cool for 20 minutes in the fridge.

In a large bowl, beat softened cream cheese with powdered sugar until smooth. Gradually fold in whipped topping in batches until well integrated.

Spread cream cheese filling over cooled crust. Pour cooled peach mixture over the cream cheese layer. Refrigerate for 4-5 hours to set.

Once set, remove from fridge. Top with additional whipped cream if desired. Cut into squares and garnish with fresh peach slices or mint.