Preheat oven to 350°F.
Grease an 8x8 dish with cooking spray.
In a large bowl, cream sugar, butter, & egg with a mixer until light and fluffy.
¾ cup white sugar, ¼ cup butter, 1 egg
In a separate bowl combine flour, baking powder, and salt. Whisk together.
1 ½ cups flour, 2 teaspoons baking powder, ½ teaspoon salt
Add a small amount to the sugar mixture, alternating with milk mixing just until combined.
½ cup milk
Toss blueberries with 1 tablespoon flour. Gently fold into the batter.
1 Tablespoon flour, 1 cup fresh blueberries
Carefully spread in the prepared pan.
Make the topping by combining the topping ingredients in a small bowl. Cut together with two forks or a pastry cutter.
5 Tablespoons butter, ¼ cup brown sugar, ¼ cup white sugar, ⅓ cup all-purpose flour, ½ teaspoon ground cinnamon
Sprinkle over batter and bake 40-45 minutes or until a toothpick comes out clean.