Blackberry Cobbler

3 cups fresh or frozen blackberries
1 cup sugar
1/4 teaspoon cinnamon
3 Tablespoons cornstarch
1 cup cold water
1 Tablespoon butter

Biscuit Topping:
1 1/2 cups flour
1 Tablespoon sugar
1 1/2 teaspoon baking powder
1/2 teaspoon salt
1/2 cup cold butter
1/2 cup milk

In a large saucepan, combine the blackberries, sugar and cinnamon. Cook and stir until smooth; stir until until mixture come to a boil. Combine the cornstarch and water until smooth; stir into fruit mixture. Bring to a boil; cook and stir for 2 minutes or until thickened. Pour into a buttered cast iron skillet. Dot with butter.
For topping, in a small bowl, combine the flour, sugar, baking powder and salt. Cut in butter until mixture resembles coarse crumbs. Stir in milk just until moistened. Drop by tablespoonfuls onto hot berry mixture.
Bake uncovered, at 350 for 30-35 minutes or until filing is bubbly and topping is golden brown. Serve warm with whipped topping or ice cream.