Finely grate the parmesan and pecorino
Cook spaghetti in a large pot of salted water until al dente or according to package instructions, approx 8 minutes. Reserve about 100ml of the pasta water and drain.
Add 1 table spoon olive oil to a large skillet on medium heat. Sauté guanciale or pancetta until crisp and fat is rendered
In a bowl mix the egg yolks with half the parmesan and pecorino and a few grates of pepper. Beat until combined
Transfer pasta along with a ladle of the reserved pasta water to the skillet with the guanciale or pancetta. Add the egg mixture, quickly mixing everything together making sure the eggs don’t scramble. Stir and toss until the mixture forms a smooth and creamy sauce that covers the pasta. Add some pasta water as needed
Serve with some parmesan, pecorino and pepper to taste. Enjoy