Kentucky Blackberry Cobbler

6 cups fresh blackberries

2 teaspoons lemon juice

1 cup white sugar

2 teaspoons cornstarch

¼ cup cold butter, cubed

4 cups all-purpose flour

¼ cup white sugar

1 teaspoon ground cinnamon

1 tablespoon salt

1 tablespoon baking powder

2 teaspoons baking soda

1 cup chilled butter, diced

1 ⅓ cups buttermilk, plus additional for brushing

¼ cup white sugar

Preheat an oven to 375 degrees F (190 degrees C). Butter a 9x13-inch baking dish.

Place the blackberries in a mixing bowl, and sprinkle with lemon juice. Toss with 1 cup sugar and cornstarch until evenly coated. Place into the prepared baking dish, and arrange the cubes of butter on top. In a large bowl, whisk the flour, 1/4 cup sugar, cinnamon, salt, baking powder, and baking soda together. Cut in 1 cup of chilled, diced butter using a pastry cutter until the butter is in pieces no larger than a pea. Stir in the buttermilk until a batter has formed. Spoon the batter evenly over the blackberries. Brush the top of the batter with additional buttermilk to moisten, then sprinkle with the remaining 1/4 cup of sugar.

Bake in the preheated oven until the the fruit is tender, and the biscuit top is golden, about 25 minutes.