Preheat oven to 375°.
In a large mixing bowl, beat butter 30 seconds until creamy.
Add brown sugar, granulated sugar, baking powder, baking soda, cinnamon, and salt. Mix until combined.
Beat in eggs and vanilla until combined.
Mix in flour; stir in oats.
Refrigerate dough 30 minutes; divide in half and add frozen blueberries to half at a time.
Scoop dough into 2 Tbsp. size balls; place 2 inches apart on an ungreased cookie sheet.
Bake at 375° for 15 minutes or centers are completely set and cookies are golden brown.
Cool 10-15 minutes on cookie sheet; remove to wire rack to cool completely.