As Ralph Waldo Emerson said, "It is a happy talent to know how to play." Baking an apple pie from scratch is a creative form of play. And you can share the fruits of your labor with friends and family. Have fun!
Preheat oven to 400º.
In a bowl, whisk together the sugar, cornstarch, cinnamon, and salt; set aside.
On a lightly floured Silpat®, roll out the larger pie dough disk into 13" circle. As you are rolling out the dough, check to be sure that there is some flour under the dough so that it doesn't stick to the Silpat®.
Place the dough in a Pyrex® pie plate.
Toss the apples with the sugar mixture and lemon mixture.
Pour into the dough-lined pie dish.
Slice the 2 T. butter into bits and place on the apples.
Roll out the remaining pie dough.
Place on top of the pie.
All around the pie, turn under the edges of the pie dough.
All around the pie, crimp the edges.
In a small bowl, whisk the egg and water.
Lightly brush onto the apple pie.
Make 3 to 4 slits in the top crust.
Sprinkle with Demerara sugar.
Bake for 45 to 60 minutes. During the last 15 to 20 minutes, cover the edges of the pie crust to prevent burning.
Or . . .
The pie may be frozen for a couple of months.
Preheat oven 400º.
Remove from freezer, brush with egg wash, sprinkle with sugar, and bake for 2 hours. During the last 30 minutes of baking, cover the edges of the pie crust to prevent burning.