In a large bowl, whisk together the eggs, salt and pepper to taste and Parmesan. Set aside.
Turn on the broiler. In a 12-inch ovenproof non-stick or cast iron skillet, heat the olive oil over a medium flame. Add the pancetta and cook, stirring frequently, until it starts to crisp, 3 to 5 minutes. Add the onion and cook until it softens a bit, about 3 minutes.
Add the greens and herbs and cook for one minute. Pour the eggs into the skillet, stir gently and cook undisturbed until almost set, about 5 minutes. Put the skillet under the broiler (about 4 inches from the heat) for a couple of minutes, until the eggs have set. Let cool for a few minutes before serving.