In a medium saucepan, stir together the sugar, cornstarch, and salt. Add the water then bring the mixture to a gentle boil, whisking often, until it forms a thick gel-like consistency. Stir in the jello and continue to cook until completely dissolved. Remove from heat and allow to cool while you prepare the remaining ingredients.

Combine the graham crackers, butter, and brown sugar in a bowl then press the mixture into the bottom of a 9 x 13 inch pan.

In the bowl of an electric mixer, beat the cream cheese and powdered sugar until smooth. Beat in the whipped topping. Spread the mixture over the graham cracker crust. Top with sliced peaches.

Once the jello mixture has cooled to room temperature or is just barely warm, pour it over the peaches. Cover and refrigerate at least 2 hours or overnight. Serve cold.