This one has other fruit in it. I am sure you could leave it out and add more blackberries. I have not tried it but it sounds really good to me.
Cobbler
Filling:
3 pounds ripe peaches, peeled, pitted and sliced, about 8 cups
1/2 pint blackberries
1/2 pint blueberries
2 tablespoons lemon juice
1 cup sugar
2 tablespoons tapioca flour
Dough:
2 cups all-purpose flour, plus more as needed
2 tablespoons baking powder
1/2 cup sugar
1/4 cup brown sugar
1/2 cup buttermilk
Topping:
1/2 teaspoon ground cinnamon
1 teaspoon sugar
2 tablespoons unsalted butter, cut into 8 small pats
Directions
Preheat an oven to 350 degrees F.
Filling: Add the fruit to a large bowl and sprinkle with lemon juice, sugar and tapioca flour. Toss the ingredients until they are coated.
Dough: In a food processor, combine the flour, baking powder and sugars and pulse 3 to 4 times. Slowly pour in the buttermilk and mix until the dough comes together. Remove the dough from the processor and turn out on a lightly floured board. Divide the dough into 3/4 and 1/4 portions. Press the larger amount into the bottom of a 12-inch cast iron skillet. Add the filling and top with 6 to 8 even dollops of the remaining dough.
Topping: Sprinkle the dough tops with the cinnamon and sugar and evenly dot the butter over the cobbler. Put the skillet in the oven and bake until bubbly, about 50 minutes. Remove from the oven and let cool for 15 minutes. Serve hot.