Preheat oven to 400 degrees F. Line a baking sheet with aluminum foil (this is to catch the blackberry juice that usually boils over from the baking dish or skillet).
If using fresh blackberries, wash, stem, and drain blackberries.
In a large bowl, combine sugar, flour, blackberries, lemon juice, and blackberry liqueur. Pour into prepared baking dish or skillet.
Prepare Biscuit Topping; set aside until ready to use.
Bake the blackberry cobbler (without the biscuit topping), uncovered, approximately 15 to 20 minutes or until hot and bubbly. When blackberry mixture is hot, remove from oven and spoon the prepared Biscuit Topping mixture onto the top in 10 to 12 large spoonfuls. Return to oven and bake another 20 to 25 minutes or until biscuits are lightly browned and a toothpick inserted in the center of one of the dumplings comes out clean.
Remove from oven and cool on a wire rack for at least 10 minutes before serving. Serve either warm or room temperature. To serve, top with vanilla ice cream.
2 cups all-purpose flour
4 teaspoons baking powder
3 tablespoons granulated sugar
1 teaspoon salt
Zest (peel) of 1 lemon
1/2 cup chilled butter, cut into 1/4-inch pieces
2/3 cup milk
1 egg, slightly beaten
In a large bowl, sift together flour, baking powder, sugar, salt, and lemon zest.
With a pastry blender or two knives, cut in butter until particles are the size of small peas. Add milk and egg; stir with a fork just until blended. Set aside until ready to use.