Preheat the oven to 350 degrees.
Melt butter in a deep one and one half quart casserole. Combine flour, ¾ cup sugar, baking powder, salt and milk. Mix throughly.
Pour the batter evenly into the melted butter without stirring.
Combine the blackberries with the other ¾ cup sugar; pour into the middle of the batter without stirring.
Bake for 30 minutes or until lightly browned.
Serve warm with ice cream.
* Either Gluten-Free or Dairy-Free