Preheat oven to 350 degrees. Rinse the blackberries & pat dry. Butter a baking dish - a deep dish pie dish works well.
Melt butter in the microwave.
Mix together one cup sugar & the flour in a mixing bowl. Whisk in the milk and mix well. Whisk in the butter, mixing well again.
Pour the batter into the buttered baking dish. Sprinkle blackberries over the top of the batter; distributing evenly. Sprinkle ¼ cup sugar over the top.
Bake for 1 hour, or until golden and bubbly. You can sprinkle an additional teaspoon of sugar over the cobbler 10 minutes before it’s done.
Let cool & serve with vanilla ice cream, of course!