Roll out half of your pastry dough. Using a 9-inch pie pan, line the bottom with it.
Using a large bowl, mix the sugar, flour, cinnamon, salt, and nutmeg.
Peel, core, and slice the apples.
Add the apples to the bowl with the sugar mixture and toss well to coat all of the apples.
Put the apples into the pie pan. Scatter small pieces of the butter over the apples.
Roll out the rest of the pastry dough and cover the top of the pie. Crimp the sides together. Poke holes into the top with a fork (or make small slits with a knife)
Put the pie into the 425 ºF oven and bake for 10 minutes
Lower the heat to 350 ºF and bake for another 30 or 40 minutes. When done the apples will feel tender when poked with a tooth pick and the crust will be a light golden brown.