To prepare filling, combine peaches, sugar, cornstarch and salt. Toss well.
To prepare crust, combine flour, sugar and salt, in a food processor and pulse until blended. Add chilled butter in small pieces and pulse until mixture is the size of coarse meal. Add water and pulse until mixture comes together. Gather into a ball, and roll out on a floured surface slightly larger than a shallow 3-quart baking dish.
Place peaches in baking dish and cover with dough. Fold under edges. Sprinkle with sugar. Make slits in top and bake 30 to 45 minutes.