Put the oats in a food processor and pulse until they are a coarse texture, but not quite powdery.
In a medium bowl, combine the oats, peanut butter (or other nut butter) and honey and mix until it forms a dough. (Add a little water if it is too dry).
Put the cocoa powder or powdered sugar (optional) in a small shallow dish.
With wet hands, roll 10 – 15 small balls of dough.
Roll the balls in the cocoa powder or powdered sugar (optional) and serve immediately or refrigerate, tightly covered, for up to a week.