Preheat a 6-inch waffle maker according to its manufacturer’s directions. Set a wire rack over a baking sheet.

Add the oats, cottage cheese, eggs, milk, baking powder, vanilla, cinnamon and salt to the blender. Blend until no obvious oat flakes or curds remain, stopping to scrape the sides if needed.

Let the batter rest for 5 minutes so the oats can hydrate. It should pour slowly. If almost spoonable, add milk 1 teaspoon at a time until it pours.

Brush the hot plates lightly with some of the oil. Add about one-quarter of the batter, or the amount recommended for your waffle maker, leaving room for it to spread. Close and cook for about 4–5 minutes, until golden, the center is set and the waffle releases without tearing. Use your appliance’s instructions and doneness cues rather than the timer alone.

Lift the waffle onto the rack. Repeat with the remaining batter and oil, letting the maker reheat between batches. The batter makes about 4 six-inch waffles; yield and cooking time vary with the iron.

Serve promptly with optional blueberries and plain Greek yogurt. For leftovers, refrigerate in a covered container within 2 hours, or 1 hour above 90°F (32°C). Keep at 40°F (4°C) or below, use within 3–4 days and reheat to 165°F (74°C).