Heat the oven to 375°F and spread the blackberry filling and frozen berries in a 9-by-13-inch baking dish.

Cut each biscuit into quarters and arrange the pieces over the fruit with open gaps.

Brush the dough with melted butter and sprinkle with coarse sugar.

Bake for 30 to 35 minutes until the biscuit centers are cooked, their tops are browned and filling bubbles in the middle.

Rest 30 minutes before serving.