Combine the first 3 ingredients in bowl. Cut in butter until crumbly, sprinkle in 1/2 cup water and make into ball, roll out 1/2 the dough to fit 12x18 jelly roll pan.
mix apples 1 1/2 cups of sugar 1 1/2 tablespoons cinnamon, nutmeg and 2 tablespoon of flour in large bowl. Spread over bottom crust. Roll out second 1/2 of dough and place over apples. crimp edges like you would a regular pie. Cut slits in top crust.
beat egg and brush over the crust and dust with sugar cinnamon mixture
Bake for 15 minutes then lower temp to 350 and bake for 30 minutes or until golden brown
I drizzle the powder sugar glaze (powder sugar/milk) over the pie about 5 minutes after it has come out of the oven. Cut into squares and serve. Enjoy!!