Allow frozen peaches and pie crusts to sit at room temperature for approximately 15 minutes.

Meanwhile, preheat the oven to 375°F (190°C). 

On a floured work surface, gently unroll one pie crust, dusting both sides with flour. Use a rolling pin to stretch the crust slightly, if necessary.

Grease a 9-inch pie pan with butter or non-stick cooking spray. Then, place the dough on the bottom of the greased pie dish. 

In a large bowl, combine frozen peach slices, sugar, flour, cinnamon, nutmeg, and diced butter.

Pour the peach mixture into the unbaked pie crust.

Gently unroll the second pie crust on the floured work surface.

Cut it into 8 strips and arrange them in a striped or lattice pattern over the peaches.

Brush the top of the cobbler with the beaten egg, discarding any excess. Fold the edges of the top crust under. To prevent over-browning, loosely cover the edges with strips of aluminum foil or pie crust shields.

Place in oven and bake for approximately 1 hour, or until it is golden-browned and bubbly.

Allow peach cobbler to cool on a rack for about 30 minutes before serving.