Spray a 9×13-inch baking dish lightly with nonstick cooking spray.
In a medium mixing bowl, stir together the graham cracker crumbs and granulated sugar.
Add the melted butter and mix until the crumbs are evenly coated.
Press the crumb mixture firmly into the bottom of the prepared baking dish. Chill for 20 to 30 minutes.
In a large mixing bowl, beat the softened cream cheese until smooth.
Add the powdered sugar and vanilla extract. Beat until creamy and fully combined.
In a separate bowl, beat the cold heavy whipping cream until stiff peaks form.
Fold the whipped cream into the cream cheese mixture.
Fold in the thawed whipped topping until the filling is smooth and fluffy.
Spread the cream mixture evenly over the chilled crust.
Arrange the drained peach slices over the cream layer.
In a medium bowl, whisk the peach gelatin with boiling water until fully dissolved.
Stir in the cold water and lemon juice.
Let the gelatin mixture cool for 15 to 20 minutes, until slightly thickened but still pourable.
Slowly pour or spoon the gelatin mixture over the peaches.
Cover the pan and refrigerate for at least six hours, or overnight.
Garnish with whipped topping, graham cracker crumbs, and extra peach slices if desired.
Slice into squares and serve chilled.