While the dough chills, peel and slice peaches then combine with brown sugar, flour, cinnamon, and nutmeg in a large bowl and mix until peaches are well coated. Mix in lemon juice.
3 pounds peaches, ½ cup brown sugar, 3 tablespoons all-purpose flour, 1 teaspoon ground cinnamon, ½ teaspoon ground nutmeg, juice of 1 lemon
Melt butter in a large skillet over medium heat and add the filling mixture to the pan. Cook until bubbly and thickened, stirring as necessary (about 5-10 minutes). Remove from heat.
¼ cup unsalted butter
Preheat oven to 350 degrees. Pour prepared filling into a square 8 x 8-inch baking pan. Set aside.
Roll out the chilled dough to about ¼ inch thickness and cut into 8 one-inch strips. Lay the strips over top of peach filling in a lattice or criss-cross pattern.
Brush the dough with beaten egg then sprinkle with granulated sugar.
1 egg, 1 teaspoon granulated sugar
Bake cobbler for about 45 minutes or until crust is golden brown and filling is thick and bubbly. Allow it to cool and set for at least another 45 minutes then serve.