In a large mixing bowl, combine flour, sugar, and salt.

Add chilled butter and vegetable shortening to the flour mixture.

Use a pastry blender or two knives to cut the butter and shortening into the flour until the mixture resembles coarse meal.

Drizzle 6 tablespoons of ice water over the mixture.

Knead with your hands just until moist clumps form, adding more ice water by teaspoonfuls if the dough is dry.

Gather the dough into a ball and flatten into a disk.

Wrap the dough in plastic wrap and chill in the refrigerator for about 30 minutes.

Roll out the dough on a lightly floured work surface as for a pie, but cut it into an 8-inch square.

Set the 8-inch square dough aside. Save remaining dough.

Preheat oven to 475°F (246°C).

In a Dutch oven or large pot, combine the sliced peaches, sugar, flour, cinnamon, and nutmeg.

Let the mixture sit until the sugar is dissolved and a syrup forms.

Over medium heat, bring the peach mixture to a boil, then reduce heat to low and cook until the peaches are tender, about 10 minutes.

Remove from heat and stir in the melted butter.

Spoon half of the peach mixture into a lightly buttered 8-inch square Pyrex dish.

Cover the peach mixture with the prepared pastry square.

Bake in the preheated oven for 12 to 14 minutes, or until lightly browned.

Spoon the remaining peach mixture over the baked pastry.

Roll out the remaining pastry and cut into strips about an inch wide.

Arrange the strips in a loose lattice weave over the peach mixture.

Bake for an additional 15 to 20 minutes, or until the pastry is browned.