Start by making the pie crust. In a large mixing bowl, combine the flour, sugar, and salt. Add the cold, cubed butter and use a pastry cutter or your hands to work the butter into the flour until the mixture resembles coarse crumbs.
Gradually add the ice water, a tablespoon at a time, and mix until the dough comes together. Divide the dough into two equal portions, shape them into discs, wrap in plastic wrap, and refrigerate for at least 1 hour.
1. Preheat your oven to 425°F (220°C).2. In a large bowl, combine the sliced peaches, granulated sugar, brown sugar, cornstarch, cinnamon, nutmeg, and lemon juice. Toss until the peaches are evenly coated.
1. Roll out one of the chilled pie crusts on a floured surface to fit a 9-inch pie dish. Place the crust in the pie dish, trimming any excess dough from the edges.2. Pour the peach filling into the pie crust.
1. In a small bowl, whisk together the beaten egg and milk to create the egg wash. Brush the top of the pie crust with the egg wash.2. Cut a few slits in the top crust to allow steam to escape during baking.
1. Place the pie on a baking sheet to catch any drips and bake in the preheated oven for 45-50 minutes, or until the crust is golden brown and the filling is bubbly.2. Allow the pie to cool completely before serving.