Your dough needs to be prepped and refrigerated beforehand.
Preheat the oven to 385 degrees.
Line a baking sheet with parchment.
Slice the peaches to ½ inch thick. Combine the sugar and cornstarch in a small bowl..
Mix fruit, sugar, and cornstarch gently with a rubber spatula.
Roll pie dough into a 20-inch circle on a lightly floured surface.
Pour fruit in the center of the pie dough. Leaving about 2 inches all the way around without filling.
Fold the edges over the fruit and pleat the edges as you do.
Combine egg wash and milk. Mix well. Brush edges of dough with egg wash.
Sprinkle with sugar, then move it to the preheated oven.
Bake until edges are golden brown and fruit is cooked, but not mushy. If the fruit is cooking too quickly, turn oven on broil and bake the crust more quickly.
Remove from oven. Let it cool slightly.