Preheat and prep: Set the oven to 425°F (220°C).
Place a rack in the lower third and set a rimmed baking sheet on it to catch drips.
Thaw the crusts: If frozen, let the pie crusts sit at room temperature until pliable but still cool. Keep one in the fridge while you work on the filling.
Prep the apples: Peel, core, and slice apples about 1/4-inch thick. Aim for even slices so they cook uniformly.
Toss the filling: In a large bowl, combine apples with granulated sugar, brown sugar, lemon juice, cinnamon, nutmeg, allspice (if using), salt, and cornstarch.
Stir until every slice looks lightly coated and glossy.
Line the pie dish: Fit one crust into a 9-inch pie dish, letting excess hang over the edge. Gently press into the corners without stretching.
Fill the pie: Spoon the apple mixture into the crust, mounding slightly in the center. Dot the top with small pieces of butter.
Add the top crust: Place the second crust over the apples.
Trim excess so there’s about 1 inch overhang, then fold and crimp the edges to seal.
Vent and glaze: Cut 4–5 small slits in the top crust for steam. Brush with egg wash and sprinkle with coarse sugar, if using.
Bake hot to set the crust: Place the pie on the preheated baking sheet. Bake at 425°F (220°C) for 20 minutes.
Reduce and finish: Lower the oven to 375°F (190°C) and bake 30–40 more minutes, until the crust is deep golden and you see thick, steady bubbling through the vents.
Cool before slicing: Transfer to a rack and let cool for at least 2–3 hours.
This helps the filling thicken so slices hold together.
Serve: Slice and serve as is, or add vanilla ice cream or whipped cream.