Preheat the oven to 425 degrees F.
Take the pie crust out of the fridge. It has to sit out at least 15 minutes.
Peel, core, and cube the apples. Set aside.
Wash the cranberries, removing any stems.
Stir the apples and cranberries together in a large bowl.
Add the sugar and spices to the apples and cranberries and stir to combine.
Add the cornstarch and stir to combine. Set aside.
Carefully unroll the dough and place on a lightly floured surface.
Roll out the dough to about a 12-inch circle.
Use a biscuit cutter or circular cookie cutter to cut out 16 disks. You may need to bunch up the scraps and re-roll the dough to cut additional circles.
Lightly spray a 9-inch square baking pan with cooking spray.
Pour the fruit filling into the prepared baking pan.
Layer the disks of dough on top of the filling. Each disk of dough should overlap a bit. Most of the surface of the fruit should be covered. It is like a lattice top, but less complicated.
Add the water to a beaten egg in a small bowl.
Brush the egg wash over the surface of the dough.
Lightly sprinkle with cinnamon sugar if desired.
Put the baking pan on a baking sheet and place it on the middle rack of the oven.
Bake at 425 degrees for 15 minutes.
Lower the oven temperature to 350 degrees F and bake for an additional 35 minutes or until the crust is golden brown and the fruit bubbling.
This is a delicious pie to serve slightly warm, but let it cool down a bit first.