Preheat oven to 350F degrees. Spray a 9 x 9 square baking dish with nonstick cooking spray and set aside.
In a medium bowl, stir together the flour with 1 cup of the sugar. Add in the milk and then pour in the melted butter and vanilla extract. Stir until combined.
Spread mixture into a prepared baking dish and top with blueberries. Sprinkle with remaining 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. We loved ours topped with additional blueberries and a scoop of vanilla ice cream! Enjoy!