Preheat your oven to 350F (175C) and grease a 9×9 inch baking pan.
In a bowl, combine the 1 cup sugar, 1/2 cup flour, and cinnamon for the topping, then cut in the cold butter until the mixture forms coarse crumbs; set aside.
In a large mixing bowl, cream together the softened butter and sugar until light and fluffy.
Add the eggs one at a time, followed by the vanilla extract, mixing well.
Whisk together the 2 cups flour, baking powder, and salt.
Gradually add the dry ingredients to the butter mixture, alternating with the milk, until smooth.
Gently fold in the fresh blueberries.
Spread the batter into the prepared baking pan.
Evenly sprinkle the prepared crumb topping over the top of the batter.
Bake for 45 minutes or until a toothpick inserted into the center comes out clean.
Allow to cool slightly before serving.