Whisk together the eggs, egg whites, chives or scallions, dill, and salt until evenly colored and foamy. In a separate bowl combine the cottage cheese, watercress, Parmesan and set aside.
Heat a skillet and add the oil to coat the bottom. Pour in the eggs, cover and cook for about 10 minutes.
When the edges of the omelet are firm and the center solid, spoon the watercress dill mixture onto the middle of the omelet. Using a spatula, fold half the omelet up and over the filling, cover and reduce the heat.
After about two minutes, flip the omelet to brown the other side for another 2 minutes. Serve immediately.