Heat the Oven - Set the oven rack to the middle position. Preheat to 425ºF (218ºC).
Grease Baking Dish - Grease a 9x13-inch baking dish with softened butter. Set aside.
Peel the Peaches - Remove the skin from the peaches using a hand peeler. Alternatively, for soft peaches that are hard to peel, use the blanch and shock method. Cut a shallow 2-inch wide “X” on the bottoms. Submerge one to two peaches at a time in boiling water until the skin starts to separate from the flesh, about 10 to 20 seconds. Immediately transfer to a bowl of ice water and cool for 1 minute, then use your fingers to remove the skin.
Prepare the Filling - Cut the peaches into ½-inch thick wedges and transfer to a large mixing bowl. This should yield about 8 cups of sliced peaches. Add brown sugar, flour, lemon juice, cinnamon, ginger, salt, and nutmeg. Stir to combine.
Pre-Bake the Peaches - Spread the peach filling evenly in the baking dish. Bake until the filling starts to bubble and lightly thicken, 15 minutes. Remove the baking dish from the oven.
Prepare the Topping - In a medium bowl, whisk together flour, granulated sugar, baking powder, baking soda, and salt. Toss the cold cubed butter into the flour mixture. Use fingers to break into small pieces until the mixture resembles cornmeal or wet sand. Stir in the buttermilk; the topping will be wet and look like a very thick cake batter.
Assemble the Cobbler - Drop about 2 tablespoon-sized mounds evenly on top of the peach filling, about 12 mounds. In a small bowl, combine granulated sugar, cinnamon, and ginger. Evenly sprinkle over the topping and filling.
Bake the Cobbler - Bake until the topping is golden brown, about 25 to 30 minutes.
To Serve - Cool the cobbler for 20 to 30 minutes before serving. This will allow the filling to thicken. Serve with a scoop of ice cream or whipped cream if desired.
Notes
For a Sweeter Filling: Add ½ cup of brown sugar instead of ⅓ cup.
For a Thinner Filling: Use 2 tablespoons all-purpose flour.
Using Frozen Peaches: Do not defrost. Follow all directions, except cook the peaches in the oven for 20 minutes before adding the topping.
Using Canned Peaches: Use 2 tablespoons all-purpose flour since there will be less moisture for thickening. Increase to 1/4 up if needed.
Sliced Peach Quantity: Use 8 cups of sliced peaches for the recipe.
Make Ahead: The peaches can be peeled and sliced 1 day ahead. Bake, cool and refrigerate the cobbler for up to 2 days.
Reheating: Bake in a 375ºF (191ºC) oven until the filling and biscuit topping is warm, about 15 to 25 minutes. This varies depending on if you are reheating the entire baking dish or just a small portion. Reheat individual portions in the microwave in 30-second intervals on high power, 60 to 90 seconds.
Leaving the Peach Skin On: The thin fuzzy fibrous skin will make it a little tougher to chew.