Add the protein powder to a small bowl, then add the hazelnut butter and syrup. Stir until protein powder has dissolved.
Scoop ¼ of the mixture and roll into a ball, and do the same with the rest of the mixture. Put the balls on a plate and freeze for about 30 minutes. Flatten the balls into cookies (or keep them in ball form).
Feel free to add ½ tsp of cocoa powder to the recipe!