In a small bowl, beat together the eggs and cheese; set aside.
In a large skillet, fry the bacon and onion together until the meat is browned and crispy and the onion has begun to caramelize.
Add the pasta (if using cold day-old pasta, cook until it’s just warmed through, about 1 minute).
Pour the egg-and-cheese mixture into the skillet and reduce heat to low. Stir continuously until the pasta is coated with the eggs and they have begun to solidify.
Season with the salt and pepper, then serve immediately, with extra grated Parmesan on the side.
This dish offers the perfect opportunity to use up leftover pasta. (PS: It also makes a fantastic breakfast.)
