Instructions:
Preheat the oven to 350 degrees F (175 degrees C) and grease and flour an 8×8 inch baking pan.
In a medium mixing bowl, combine flour, 1/2 cup sugar, baking powder, baking soda, and salt.
In a separate mixing bowl, cream together butter and sour cream.
Beat in eggs and vanilla extract.
Gradually add the dry ingredients to the wet ingredients, mixing until well combined.
Gently fold in the blueberries.
Pour the batter into the prepared baking pan.
In a small mixing bowl, combine 1/2 cup flour, 1/2 cup sugar, and cinnamon. Cut in butter until mixture resembles coarse crumbs.
Sprinkle the topping evenly over the batter.
Bake for 40-45 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and let it cool completely before serving.
Enjoy!!