Pre-heat oven to 325 and grease 13” x 9” baking dish.
Place flour, condensed milk, plain milk, and melted butter into large bowl. Mix with large spoon or whisk until blended. Pour into the greased baking dish.
Slice blackberries in half, lengthwise. Spread blackberries evenly across top of batter, flat side down, saving a few for garnish.
Sprinkle the brown sugar evenly on top of the blackberries.
Bake in oven for 35-40 minutes until light golden brown and toothpick inserted into center comes out clean.
Let cool on rack for 10 minutes.
Serve with ice cream or whipped cream and a few blackberries. (Whipped cream with vanilla flavoring is shown in the top photo)
The cobbler can also be baked in a liberally buttered, oven-proof stoneware pie dish.