Heat the oven to 425°F with a rimmed sheet pan on the lower rack.
Toss the apples with the sugar, flour, cinnamon, nutmeg and lemon juice.
Roll one dough disk into a 12-inch circle, fit it into a 9-inch pie plate, and mound in the apples before dotting them with butter.
Roll the second disk, cover the pie, trim and crimp the edge, cut 5 steam vents, and brush with egg wash.
Set the pie on the hot pan, bake for 20 minutes, lower the heat to 375°F, and bake 40 to 45 minutes more until thick juice bubbles through the vents.
Cool for at least 3 hours before slicing.