Preheat oven to 375F.

Beat the butter and sugar till smooth.

Add egg and vanilla and mix until well combined.

Stir in flour, baking powder, salt, and cinnamon. Mix until dough comes together.

Add in milk. If dough is still crumbly, then add more milk, one tablespoon at a time, till it comes together.

Gently fold in the blueberries. I used my hands for that part.

Refrigerate for 30 minutes.

Roll dough into 1″ to 1-1/2″ balls and bake at 375F for 10-12 minutes.