In a medium bowl, sift together the flour, 3 tablespoons sugar, and salt. Work in the shortening with a pastry blender until the mixture resembles coarse crumbs. In a small bowl, whisk together the egg and cold water.
Sprinkle over flour mixture, and work with hands to form dough into a ball. Chill 30 minutes.
Preheat oven to 350 degrees F (175 degrees C).
Roll out half of dough to 1/8 inch thickness.
Place in a 9x13 inch baking dish, covering bottom and halfway up sides.
Bake for 20 minutes, or until golden brown.
In a large saucepan, mix the peaches, lemon juice, and orange juice.
Add 1/2 cup butter, and cook over medium-low heat until butter is melted. In a mixing bowl, stir together 2 cups sugar, nutmeg, cinnamon, and cornstarch; mix into peach mixture.
Remove from heat, and pour into baked crust.
Roll remaining dough to a thickness of 1/4 inch.
Cut into half-inch-wide strips. Weave strips into a lattice over peaches.
Sprinkle with 1 tablespoon sugar, and drizzle with 1 tablespoon melted butter.
Bake in preheated oven for 35 to 40 minutes, or until top crust is golden brown.