In a small bowl, whisk together the eggs, egg yolks, Parmesan, Pecorino and pepper; set aside. (Tip: Do this first to allow egg mixture to come to room temperature before using it later in the recipe.)

Fill a large stock pot with 6 quarts of water and salt liberally. Heat over high until boiling. Add spaghetti and cook for 8-10 minutes, or until al dente. Reserve 1 cup of the pasta water; Drain rest of pasta water into a large serving bowl. (See note below)

While the pasta is cooking, add the cubed pancetta to a deep frying pan over medium-low heat; cook for 7-8 minutes or until slightly crispy.

Add cooked pasta and ¼ cup of reserved pasta water to pan with the cooked pancetta; stir well and cook over medium heat for 1 minute, or until most of the water has evaporated.

Pour water out of the large serving bowl. Transfer pasta and pancetta into the bowl, and stir in the egg mixture. Stir constantly until eggs begin to thicken and coat the spaghetti. (The heat from the pasta and bowl will indirectly cook the eggs. If the mixture becomes too thick, add a splash of the reserved pasta water. I typically add about 1/4 cup of additional pasta water at this point.)

Top liberally with freshly ground black pepper and additional Parmesan cheese. Serve immediately.