Combine the blackberries, 1 cup of sugar, cornstarch, and lemon juice in a large mixing bowl. Stir gently until the blackberries are evenly coated and the mixture is slightly thickened. Transfer the berry mixture to a baking dish, spreading it out evenly. Bake at 375°F (190°C) for 15 minutes or until the mixture starts to bubble around the edges.
4 cups fresh blackberries, 1 cup granulated sugar, 2 tablespoons cornstarch, 1 teaspoon lemon juice
Meanwhile, prepare the topping by combining the flour, 1/2 cup sugar, baking powder, and salt in a mixing bowl. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Stir in the milk until just combined, creating a thick, spoonable batter.
1 cup all-purpose flour, 1/2 cup granulated sugar, 1 teaspoon baking powder, 1/4 teaspoon salt, 1/2 cup cold unsalted butter, 1/2 cup milk
Remove the berry mixture from the oven once it is bubbling and slightly thickened. Drop spoonfuls of the batter evenly over the hot berries, covering most of the surface but allowing some to peek through for a rustic look. Return the dish to the oven and bake for an additional 25 minutes, or until the topping is golden brown and cooked through.
4 cups fresh blackberries, 1 cup all-purpose flour, 1/2 cup granulated sugar, 1 teaspoon baking powder, 1/4 teaspoon salt, 1/2 cup cold unsalted butter, 1/2 cup milk
Once baked, remove the cobbler from the oven and let it cool slightly for about 10 minutes. The top should be crisp and golden, while the berries underneath are soft and saucy. Serve warm, optionally with whipped cream or ice cream.
