Preheat oven to 375 degrees F.
Line a cookie sheet with parchment paper. Set aside.
Rinse blueberries and let drain on a paper towel. Pat dry. Set aside.
In a medium bowl whisk together the flour, salt, baking powder, and cinnamon. Set aside.
In the bowl of a standing mixer with the paddle attached, beat the brown sugar and butter for 3 minutes, or until fluffy. Make sure to scrape the sides of the bowl.
Add the egg and vanilla, and mix very well.
Add flour mixture, and mix again.
The dough will be a bit dry, so add the milk one tablespoon at a time.
Fold in blueberries.
Put 1/2 cup white sugar on a plate or piece of wax paper.
Form balls of dough and roll in white sugar. Balls should be 1 to 1.5 inches in diameter. Place balls on parchment lined cookie sheet.
Bake for 10 -12 minutes. Cookies are done when they are lightly browned around the edge.
Cool cookies on pan for 1 minute, and then remove to wire rack to cool.