Bring 6 quarts water to boil in large pot and add 2 T. salt. Mix olive oil and pancetta or bacon in 12 to 14 inch saute pan set over medium heat. Cook until the pancetta or bacon has rendered its fat and is crispy and golden. Remove form heat and set aside, but don’t drain the fat. Cook spaghetti in boiling water until just al dente. Scoop out 1/4 cup of the pasta cooking water and set aside. Drain the pasta. Add reserved pasta water to the pan with the pancetta, then toss in the pasta and heat, shaking the pan for 1 minute. Remove form heat, add 1 cup of the Parmigiano Reggiano, the egg whites and pepper to taste and toss until thoroughly mixed. Divide pasta among 4 warmed serving bowls. Make a nest in center of each serving and gently drop in an egg yolk. Season the egg yolks with more pepper and sprinkle with remaining 1/4 cup Parmigiano Reggiano. Serve at once.
Cooking the Costco way