Preheat the oven to 425 degrees Fahrenheit (190°C). Place a baking sheet on the bottom rack to catch any drips.
In a large bowl, mix the drained canned peaches, granulated sugar, brown sugar, cornstarch, cinnamon, nutmeg, and lemon juice. Gently toss until the peaches are evenly coated.
Spray the bottom of a 9-inch pie dish with nonstick spray. Then roll out one pie crust and place it in the bottom of the pie dish. Poke the crust with a fork to allow for some aeration.
Pour the peach filling into the crust and dot with butter. Cover with the second crust (whole or lattice). Trim and crimp the edges.
Beat the egg with a splash of water and brush it over the top crust. Sprinkle with coarse sugar if desired.
Cut slits in the top crust for steam to escape if using a whole top crust.
Bake for 15 minutes. Then reduce the heat to 350 and continue baking for 45-55 minutes or until the crust is golden brown and the filling is bubbling. If the crust starts browning too quickly, cover the edges with foil.
Let the pie cool at least 2 hours before slicing to allow the filling to set.