Preheat the oven to 400 degrees. Line a muffin tin with 12 liners or spray them with cooking spray.

In a large bowl combine the flour, baking powder, and salt. Mix well and set aside.

In a large bowl combine the sugar, butter, milk, sour cream, and eggs. Mix well with a wire whisk until just blended.

Add the flour mixture to the sugar mixture and mix until just combined. Gently fold in the blueberries.

Divide the batter evenly between 12 muffin cups, filling each one 2/3 of the way full.

In a small bowl combine the flour, sugar, butter, and cinnamon. Using your fingers, mix the butter into the dry ingredients until a crumb mixture forms.

Sprinkle 1 tablespoon of the crumb mixture evenly over top of all 12 muffins.

Bake the muffins for 18-22 minutes or until they are golden brown and a toothpick inserted into the center comes out clean.

Remove from the oven and cool on a wire rack.