Place peaches in a greased 13 x 9 inch glass baking dish. Combine filling ingredients (brown sugar, flour, lemon juice, and cinnamon) in a bowl. Sprinkle mixture into the peaches. Combine topping ingredients (flour, granulated sugar, baking powder, and nutmeg) in a bowl. Stir in the egg until the mixture resembles coarse crumbles. Sprinkle topping mixture over the peaches. Dot mixture with sliced butter. Bake at 375 degrees for 35-40 minutes.