Step 1: Prepare the Peaches: Wash, peel (if desired), pit, and slice your fresh peaches into 1/2-inch thick wedges. If using frozen, thaw and drain excess liquid.
Step 2: Make the Filling: In a large bowl, gently toss the sliced peaches with granulated sugar, brown sugar, cornstarch, lemon juice, cinnamon, and nutmeg. Let this mixture sit for 10-15 minutes while you prepare the topping.
Step 3: Preheat and Butter: Preheat your oven to 375°F (190°C). Lightly butter a 9x13 inch baking dish.
Step 4: Prepare the Biscuit Topping: In a separate medium bowl, whisk together all-purpose flour, granulated sugar, baking powder, and salt. Cut in the cold, cubed unsalted butter using a pastry blender, two knives, or your fingertips until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.
Step 5: Add Liquid to Topping: Gradually add the milk to the flour mixture, stirring just until a shaggy dough forms. Be careful not to overmix.
Step 6: Assemble the Cobbler: Pour the peach filling evenly into the prepared baking dish. Drop spoonfuls of the biscuit dough over the peach mixture. You can sprinkle a little extra sugar or cinnamon on top of the dough before baking.
Step 7: Bake to Golden Perfection: Bake for 40-50 minutes, or until the topping is golden brown and the peach filling is bubbling thickly around the edges. If the topping browns too quickly, loosely tent it with aluminum foil.
Step 8: Cool and Serve: Let the cobbler cool for at least 15-20 minutes before serving. Serve warm with a scoop of vanilla ice cream or a dollop of whipped cream.