Preheat oven to 350F. Spray a 9x13" pan with cooking spray. Lay the blueberries in a single layer on the bottom of the pan. Whisk together the flour, baking powder, salt, and sugar in a large bowl. Add milk, melted butter and eggs, and with a wooden spoon mix well. Pour batter over blueberries. Sprinkle top with the Tbsp. of sugar. Bake for 40-45 min. or until golden and cake tester comes out clean. Allow to cool before serving.