1. In a medium bowl, whisk together flour, protein powder, baking soda, and salt; set aside. In a large bowl, whisk together brown sugar, sugar, and melted butter until smooth. Whisk in vanilla extract and eggs until combined. Add flour mixture and whisk until just incorporated. Use a rubber spatula to gently mix in blueberries. Cover dough with plastic wrap and let chill for at least two hours and up to overnight.
2.Adjust oven racks to middle and upper positions and preheat oven to 375°F. Line two baking sheets with parchment paper. Drop dough by the rounded tablespoon onto baking sheet. Bake until golden, 13-15 minutes. Let cool 3 minutes then transfer a wrack to finish cooling.
Makes about 30 cookies. Leave to cool for two hours and enjoy!