Preheat oven to 375°.
Place peaches in a greased shallow 2-1/2-qt. Dutch oven, cast iron pan or 2-1/2-qt. ovenproof baking dish.
In a small bowl, combine brown sugar, flour, lemon juice, zest and cinnamon; sprinkle over the peaches.
Combine flour, sugar, baking powder, salt and nutmeg.
Stir in egg until the mixture resembles coarse crumbs.
Sprinkle over the peaches. Pour butter evenly over topping.
Bake 35-40 minutes. If desired, serve with ice cream.