Preheat the oven to 350 degrees. Spray a 13x9 inch baking pan with baking spray.
Whisk 2 cups of flour, baking powder, and salt in a medium bowl. Set aside.
In a standing mixer with a paddle attachment or using a hand mixer, cream the butter and brown and white sugar until light and fluffy, 3-5 minutes.
Add the eggs one at a time, mixing on low until incorporated.
Add ⅓ of the dry ingredients to the batter, mix until combined. Add half the milk. Follow by half of the remaining flour, mixing each time. Add the rest of the milk, mix and add the rest of the dry ingredients.
In a separate bowl, toss ½ a cup of blueberries with a teaspoon of flour.
Gently fold the blueberries into the batter using a rubber spatula.
Transfer the batter to the prepared baking pan and spread it out evenly. Sprinkle another 1 cup of blueberries on top of the cake.
Mix 2 teaspoons of sugar and cinnamon in a small bowl. Sprinkle the sugar on top of the cake. Bake for 40-45 minutes.
Recipe by Olga's Flavor Factory at https://www.olgasflavorfactory.com/recipes/sweets/blueberry-boy-bait/