Beat butter and sugar with an electric mixer until smooth. Add egg and vanilla, mixing well until combined, about two minutes.

Stir in flour, baking powder, salt and cinnamon with the mixer on low speed.

Add milk. If dough is still crumbly, add milk a tablespoon at a time until it just comes together

Fold in blueberries gently with a large rubber spatula. It's ok if a few break, but try not to turn your dough purple!

Refrigerate for thirty minutes lightly covered with a towel

Preheat oven to 375°F

Remove dough from fridge and roll into 1 1/2 inch balls. Set two inches apart on cookie sheet and bake at 375°F for 10 - 12 minutes.

Cool for two minutes on cookie sheet before transferring to wire rack to cool completely. Makes 12 -15 big cookies.