Preheat oven to 375°F. Lightly grease a 9×13-inch baking dish.
Press two pie crusts into the bottom and slightly up the sides of the dish, joining the dough where necessary.
Line with parchment and pie weights. Prebake for 10 minutes, then remove the weights and parchment.
Combine peaches, granulated sugar, brown sugar, cinnamon, cornstarch, and lemon juice.
Spread the peach filling over the bottom crust.
Cut the remaining two pie crusts into 1-inch strips and weave into a lattice topping.
Brush with milk and sprinkle lightly with sugar.
Bake for 40–45 minutes until golden brown and bubbling.
Rest for 20–30 minutes before serving.