Gather the ingredients so you have everything close at hand on the counter or table. Preheat oven to 400℉.
Using a pairing knife, peel, core, and slice 4 cups fresh peaches. Place in a large bowl.
Prepare the Peaches
In a medium saucepan, combine 1/2 cup brown sugar, 4 teaspoons cornstarch, and 1/4 teaspoon nutmeg (freshly grated). Add 1/2 cup water to mixture and cook till sauce thickens.
Add 1 tablespoon lemon juice and 1 tablespoon butter to the sauce, then pour over the peaches. Stir to combine.
Make the Topping
To prepare your topping, in a medium bowl, sift together 1 cup all-purpose flour, 2 tablespoons granulated sugar, 1 1/2 teaspoon baking powder, and 1/4 teaspoon salt.
Cut in 1/4 cup butter until mixture is crumbly. Create a hole in the center and add 1 large egg and 1/4 cup whole milk. Whisk together with a fork and then blend in with the flour mixture until moist.
Pour hot fruit mixture into a greased square baking dish. Spoon biscuit topping over peaches by small mounds, flattening them out with the spoon or your fingers.
Sprinkle with 2 tablespoons decorating sugar to garnish. Bake in preheated oven for 35-45 minutes until topping is cooked through. Be sure to check the topping in the center with a fork to test if it is fully baked. Serve warm with ice cream or whipped topping. Serves 4-6.
Notes
*All butter used on this recipe site is salted.**If baking with Polish Pottery or other ceramic baking dish, do not preheat oven. Allow the dish to heat in the oven at the same time to minimize risk of the dish cracking or glazing due to temperature shock. I do this with all of my Polish Pottery or other Pottery bakeware.