Roll out one pie dough disc into a 12-inch/30cm circle using a rolling pin on a lightly floured surface. Lightly dust the top of the pastry with flour, then gently roll it up the rolling pin like a spiral.
Transfer it to a pie dish and carefully unroll it from the rolling pin until it's draped over the pie plate and overhangs the sides.
Scoop the cooled cherry pie filling into the bottom crust and spread it out.
Roll out the second pie crust disc into a 12-inch circle on a lightly floured work surface. Drape this second layer on the pie to create a whole top crust.
Cut off the uneven excess dough overhang. Leave enough overhang so you can roll and pinch together the pie's top and bottom crust. Flute the edges of the pastry with your fingers.
Brush the top of the pie crust with egg wash. If you're not making a lattice top, add 3-4 slits to the pastry's top to allow steam to escape when baking.
Bake pie at 425°F/220°C for 15 minutes, then turn the oven temperature down to 375°F/190°C and continue baking for a further 25 minutes until the pastry is well browned and the filling does the occasional bubble.
If the crust shows excessive browning, you can loosely tent the top of the pie with aluminum foil. However, don't be afraid of a deep golden brown crust, which brings flavor and flakiness.
Once baked, remove the hot pie from the one and let it cool down completely to room temperature on a wire rack.