Whisk together the water and jello in a mixing bowl. Microwave on high for 1 minute. Whisk again until the jello has dissolved.
Add the yogurt and Cool Whip to the jello and whisk to combine. Then stir in the diced peaches.
Pour the pie filling into the graham cracker crust. Cover and refrigerate until set, about 1 hour or up to overnight.
Top with peach slices before cutting into 8 slices and serving. Store any leftovers covered in the fridge.
