Combine dry ingredients: In a large bowl, mix together the rolled oats, protein powder, chocolate chips (if using), and a pinch of salt.
Add wet ingredients: Add in the nut butter of choice, honey or maple syrup, and vanilla extract (if using) to the dry ingredients. Stir until well combined. If the mixture seems too dry, you can add a little more nut butter or honey/maple syrup.
Form balls: Take small portions of the mixture and roll them into balls using your hands. The size of the balls is up to your preference, but aim for bite-sized portions.
Chill: Place the formed balls on a baking sheet lined with parchment paper and refrigerate them for at least 30 minutes to firm up.
Store: Once firm, transfer the protein balls to an airtight container. They can be stored in the refrigerator for up to a week, or you can freeze them for longer storage.