Spread one 9-inch crust into bottom of pie pan. Grease pan first if you desire. Be sure to have enough of the dough overlapping the rim of the pie pan, so you can pinch it together with the top.
Peel and cut apples (about 8-10 slices per apple). Discard cores.
Heap apple slices into pie crust.
Cut butter onto the apples.
In a bowl, mix together sugar and cinnamon.
Drizzle sugar/cinnamon mixture over the top evenly.
Add top layer of crust, pinch edges together with bottom crust.
Pierce the top layer all over with a fork.
Make an egg wash in a small bowl and brush over the top, if you desire.
Bake in oven for 50 minutes.
Let stand and cool for at least 1 hour. (The pie thickens up and slices better after sitting out a bit.)