1Fill a large pot with water and bring it to a boil. Skip the salt, because the pancetta and pecorino bring plenty.
2Set the pancetta in a cold skillet and turn the heat to medium. Cook for 8 to 10 minutes, stirring now and then, until the fat has rendered and the cubes are golden and crisp at the edges. Turn off the heat and leave the pancetta and its fat in the pan.
3While the pancetta cooks, drop the spaghetti into the boiling water and cook until just shy of al dente, about 1 minute less than the package says. Stir it once or twice so it doesn't clump.
4In a large mixing bowl, whisk the eggs with the grated pecorino and the black pepper until it forms a thick, pasty sauce.
5Before draining, scoop out about 1 cup of the starchy pasta water. Lift the spaghetti straight from the pot with tongs into the skillet with the pancetta, and toss to coat it in the fat. Let it cool for 30 seconds off the heat.
6Pour the spaghetti and pancetta into the bowl with the egg mixture, and toss quickly and constantly with tongs. Splash in pasta water a few tablespoons at a time until the sauce turns silky and coats each strand. The residual heat cooks the eggs gently, and the sauce should look creamy, not scrambled.
7Serve right away in warm bowls, topped with more pecorino and another crack of black pepper. The sauce tightens as it sits, so loosen any leftovers with a splash of hot water.