Cook spaghetti in salted boiling water until al dente. In a separate bowl, whisk eggs with grated Parmesan and a pinch of pepper. In a pan, cook chopped pancetta until crisp. Drain the pasta, reserving some cooking water. Toss pasta with the pancetta, remove from heat, and quickly mix in the egg-cheese mixture, adding a splash of pasta water to create a creamy sauce. Serve hot with extra cheese.