Preheat oven to 375. Line muffin pans with paper liners or grease them.
Mix flour, baking powder, and salt, set aside.
In large bowl with electric mixer at high speed, beat butter, sugar, eggs, and vanilla until light and fluffy for 4 minutes
At low speed beat in flour mixture (in fourths) alternating with milk (in thirds), beginning and ending with flour mixture. Beat until smooth.
Gently fold in blueberries. (Frozen blueberries will be easier to mix in if they are not thawed.)
Bake for 20 to 25 minutes.