Preheat the waffle iron according to its instructions. Set a wire rack nearby. If keeping batches warm, place an oven-safe rack over a baking sheet in a 200°F oven.

Blend the oats to a coarse flour. Add the cottage cheese, eggs, milk, oil, baking powder, vanilla and cinnamon; blend until the curds disappear and the batter is mostly smooth. Let stand for 5 minutes. If too thick to pour slowly, blend in milk 1 tablespoon at a time.

Lightly grease the iron as its manufacturer directs. Add the recommended amount of batter without overfilling; the yield is approximately four standard square waffles, depending on the iron.

Close and cook without lifting for about 4–6 minutes per batch, or until golden, set through the center and releasing cleanly. Steam should have slowed considerably. Adjust heat down if the outside browns before the center is cooked.

Transfer each waffle to the rack in a single layer. Serve promptly with optional toppings. Repeat with the remaining batter, allowing the iron to recover its heat.

Refrigerate cooled leftovers promptly in a covered container at 40°F or below and use within 3 days. Do not leave perishable food out more than 2 hours, or 1 hour above 90°F. Reheat in a toaster oven until hot throughout and crisp.