Preheat oven to 375 degrees.
Line cookie sheet with parchment paper.
In a medium bowl whisk together flour, salt, baking powder and cinnamon. Set aside.
In the bowl of a standing mixer with paddle attached beat brown sugar and butter until fluffy, about 3 min. scraping sides as needed.
Add egg and vanilla.
Add flour mixture.
Dough will be a bit dry so add the milk a Tablespoon at a time. 2 T. should be plenty.
Fold in blueberries.
Put 1/2 c. white sugar on a plate or piece of wax paper.
Form balls of dough and roll in white sugar. I used a cookie scoop and dropped the scoops onto the sugar. Place balls on cookie sheet.
Bake for 12 min.
If you do not have a convection oven it is recommended that you rotate the cookie sheet halfway through the cook time.
Cool cookies on pan for 1 minute and then remove to wire rack to cool.