Traditionally, carbonara doesn't contain onions, but caramelized ones add another level of flavor. Separating the eggs before adding them to the hot pasta is a method borrowed from Mario Batali that produces a creamy mouthfeel.
- 1/2 pound pancetta, bacon or guanciale, diced
- 1 medium onion, halved and thinly sliced
- -- Freshly ground black pepper
- -- Kosher salt
- 1 pound spaghetti
- 4 eggs, separated
- 1 cup grated Parmesan cheese
Instructions: In a medium saucepan over medium heat, cook the pancetta until crisp. Remove with a slotted spoon and put on a paper towel-lined plate, reserving the drippings in the pan. Add the onions and a few grinds of pepper to the pan; cook, stirring occasionally, over medium-low heat until deeply caramelized, about 15 minutes.
Meanwhile, bring a large pot of salted water to a boil; add spaghetti and cook until al dente. Drain the 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 to combine. Add the egg yolks and Parmesan and toss to combine, adding a few splashes of reserved pasta water to achieve a creamy texture. Season to taste with salt and a generous amount of freshly cracked pepper and serve immediately.
