Peel, core, and halve apples. Cut into 1/2-inch slices, then slice into 1/2-inch cubes. Combine sugar, butter, cinnamon, nutmeg, and salt together in a large bowl; add apples and toss to coat evenly. Add flour and toss again to distribute.
Pour apple mixture into 1 pie crust. Roll out 2nd pie crust, top pie, and pinch crust edges together.
Place pie on baking sheet and bake in the preheated oven until golden brown, about 45 minutes.