In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter until the mixture resembles wet sand. Firmly press this mixture into a greased 9x13 inch pan, spreading it evenly and compressing it with the back of a measuring cup. For a firmer texture, refrigerate the crust for 30 minutes or bake at 375°F for 8 minutes, then allow to cool completely before proceeding.

In a medium saucepan over medium heat, whisk together granulated sugar and cornstarch. Gradually add cold water, stirring constantly until the mixture comes to a boil. Continue to cook for about 2-3 minutes or until it thickens and becomes clear. Remove from heat and stir in the peach Jello and diced peaches. Let this topping cool in the fridge for at least 20 minutes before pouring over the cheesecake layer.

In a large bowl, beat the softened cream cheese and powdered sugar together until the mixture is smooth and creamy. Gradually fold in the whipped topping and vanilla extract, taking care to mix thoroughly until the filling achieves a fluffy consistency. Spread this delightful cheesecake filling over the cooled graham cracker crust, ensuring an even layer that reaches the edges.

Once the peach mixture has cooled, gently pour it over the cream cheese filling, spreading it evenly to create a beautiful topping. Cover the assembled dessert with plastic wrap and refrigerate for 4-5 hours, allowing the peach topping to fully set and infuse into the cheesecake layer.

When ready to serve, remove the dessert from the refrigerator and slice into squares. Optionally, garnish each piece with extra whipped topping.