In a medium saute pan over medium heat, cook the pancetta until tender-crisp. Remove to a paper towel-lined plate and set aside. Reserve the pan with the drippings.
Separate 4 of the eggs and set the yolks aside. Discard the 4 whites. Crack the fifth egg and add it to the yolks.
In a large bowl, whisk together the egg yolks, 2/3 of the pancetta, the Parmigiano-Reggiano, black pepper and cayenne.
Cook the pasta until al dente. Add the peas when the pasta is just about finished and strain both into the reserved pancetta drippings. Reserve about 3/4 cup pasta water to fortify the sauce.
Add the egg mixture into the pasta and toss well with tongs for about 1 minute. Add the reserved pasta water to the bowl in 1/4 cup increments, combining and adding until desired sauce consistency is reached. Add the parsley and gently combine and place into a serving dish.
Garnish with the reserved pancetta.