Preheat the oven to 350°F.
Spray an 8x8 baking pan with nonstick spray and set aside.
In a small bowl, add the 1 tablespoon of flour to the blueberries and gently stir to coat blueberries with flour. Set aside.
In a medium bowl, whisk together the 2 cups of flour, baking powder, and salt (whisking will remove any lumps in the flour). Set aside.
In a large bowl, cream together the sugar, ¼ cup butter, and egg on medium-high speed with a handheld mixer for 1 to 2 minutes. Add the milk and mix on low speed until smooth, 1 to 2 minutes.
Add the dry ingredients and stir just until mixed.
Gently stir in the flour-coated blueberries.
Spread mixture evenly into the prepared pan.
In a small bowl, mix together with a fork the topping ingredients of brown sugar, 3 tablespoons flour, 3 tablespoons of butter, and cinnamon until crumbly. Sprinkle on top of the coffee cake batter.
Bake for 35 to 40 minutes or until the cake tester comes out with just a few crumbs on it. Let it sit in the pan for 10 minutes before serving.