Spoon batter onto a parchment-lined sheet as 4 cookies (use the back of your spoon to shape them into circles).
Bake for 5 minutes, and check to see if they are firm. If not, check every minute. Be sure not to over-bake these cookies! Take them out as soon as they are firm.
Let cool, and enjoy! Store in the refrigerator.
Notes
This recipe works well with whey protein, and I wouldn't try substituting other types of protein powder.