Preheat oven to 350F degrees. Spray a 9x9-inch square baking dish with nonstick cooking spray and set aside.
In a medium bowl, stir together 1 cup self-rising flour with 1 cup granulated sugar.
Add in 1 cup milk and ½ cup (1 stick) salted butter, melted and 1 teaspoon vanilla extract. Stir until combined.
Spread mixture into a prepared baking dish and top evenly with 2 cups fresh blueberries. Finally sprinkle the top evenly with ¼ cup sugar
Bake on the middle oven rack uncovered for 45 minutes - hour, until the top is a light golden brown and a toothpick comes out clean.
Allow to slightly cool before serving.
