Preheat the oven to 350 degrees F. Coat a 9 by 12-inch baking pan with cooking spray.
In a large bowl, combine the blueberries and 1/2 cup of the sugar. Toss to combine and set aside.
In a medium bowl, combine the remaining 1 cup sugar, the flour, and baking powder.
In a large bowl, beat the butter and milk together until smooth. Gradually beat in the flour mixture until smooth. Pour the batter into the prepared pan, then scatter the blueberries over the batter, letting them sink in, without mixing. Bake until the top is golden brown, 35 to 45 minutes. Let cool slightly before serving. Spoon the cobbler into bowls and top with ice cream and/or blueberries, if using.