1Preheat an oven to 375 degrees F (190 degrees C). Butter a 9x13-inch baking dish.
2Place 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.
3Bake in the preheated oven until the the fruit is tender, and the biscuit top is golden, about 25 minutes.
Ingredients
10 servings
555 cals
6 cups fresh blackberries
2 teaspoons lemon juice
1 cup white sugar
2 teaspoons cornstarch
1/4 cup cold butter, cubed
4 cups all-purpose flour
1/4 cup white sugar
1 teaspoon ground cinnamon
1 tablespoon salt
1 tablespoon baking powder
2 teaspoons baking soda
1 cup chilled butter, diced
1 1/3 cups buttermilk, plus additional for brushing