Add flour, protein powder, brown sugar, and baking powder to a bowl. Stir to combine.
Add peanut butter, mix to incorporate, then stir in milk.
Divide dough into 6 and shape each piece into a puck formation before placing them onto a parchment-lined baking sheet.
Bake for 10-12 minutes at 450F.
Serve with a warm beverage, and enjoy!
Video
Notes
When mixing your protein cookie dough, gentle is the name of the game. Stir just until ingredients combine, avoiding overworking. Overmixing leads to tough treats, and nobody wants that!
After mixing, let your protein cookie dough relax in the fridge for at least 30 minutes. This chills the fat, helps flavors meld, and improves texture.