This is so easy and simple and we loved it-it comes together super fast! The recipe is from the wonderful food section of the San Francisco Chronicle and they borrowed the technique of separating the eggs from Mario Batali. I made one half of the recipe for the two of us and it was delicious!
1/2# pancetta, bacon or guanciale, diced
1 medium onion, halved and thinly sliced
freshly ground black pepper and good salt
4 eggs, separated
1 cup grated Parmesan cheese
Cook pancetta in a medium saucepan over medium heat until crisp. Remove with a slotted spoon and drain on a paper towel, reserving drippings in pan. Add the onions and a few grinds of black pepper and cook stirring occasionally over medium low heat until deeply caramelized, about 15 minutes.
Meanwhile, bring a large pot of salted water to a boil and add the spaghetti. Cook al dente. Drain pasta, reserving 1 cup of the pasta water. Place spaghetti in a large bowl; add the pancetta onion mixture and toss to combine. Add the egg whites and toss. Add the egg yolks and Parmesan and toss, adding a few splashes of the pasta water to achieve a creamy texture. Season with salt and a generous amount of freshly ground black pepper and serve immediately!