Preheat oven to 400˚ F and position one oven rack on the bottom and one in the center.
Remove dough from the refrigerator.
On a lightly floured surface, roll out one dough disk to 1/4-inch thick. Transfer the dough to a pie plate and gently press it into the plate, leaving any excess dough hanging over the edge for crimping later.
In a large bowl, toss the cherries, sugar, cornstarch, lemon juice, cinnamon, and nutmeg together to combine thoroughly.
Pour the cherry mix into the pie plate and fold the sides of the dough up over the cherries. Set aside.
Roll out second pie dough disk to an 11-inch circle. Cut the dough into 11 1/2-inch strips.
Place 6 of the strips vertically on the pie. Weave the other 5 strips horizontally between the vertical strips to form a lattice. Trim any extra pieces and fold over the edges of the crust and crimp.
Brush the top of the dough with the beaten egg and sprinkle with sugar.
Bake the pie for 20 minutes.
Turn the heat down to 350˚ F and bake for an additional 30-40 minutes or until the crust is golden brown and the filling is bubbling.
Allow the pie to cool for 6 hours or overnight before serving.