In a medium bowl, whisk together egg whites and 1 Tbsp water; season with salt and pepper, set aside.
In a medium nonstick skillet, heat oil over medium high. Add spinach, and season with salt and pepper; cook until wilted and tender, 1 minute. Add egg whites; cook until nearly set, using a flexible heat proof spatula to pull sides of omelet toward center as uncooked egg whites run underneath, 1 to 2 minutes.
Dollop cottage cheese on top of omelet, sprinkle with Parmesan, and season with salt and pepper. Gently slide omelet onto a serving plate, folding it over on itself by tipping skillet.
