Bring a large pot of salted water to a boil. Cook the spaghetti according to the package instructions while you start the sauce.
Heat a large skillet over medium-high heat and add the oil and pancetta. Cook until the pancetta gets brown and crispy, 3 to 4 minutes.
In a bowl, whisk the eggs with the cheese and some salt and pepper.
When the spaghetti is done, drain it, reserving some of the cooking water, and add the pasta to the hot pancetta skillet. Toss to coat the pasta with the oil. Remove the skillet from the heat and pour over the egg mixture, tossing quickly so the eggs don't scramble. Add some of the hot cooking water to thin it out and form a sauce. Toss in the parsley. Serve immediately with some extra cheese and a drizzle of olive oil.