Bring a large pot of water to a boil and salt it well. Cook the spaghetti until al dente.
Cut the guanciale into small pieces. Heat a pan and add a little olive oil. Cook the guanciale until it becomes crispy and releases its fat.
In a bowl, mix the egg yolks with the grated pecorino. When the pasta is ready, reserve about a cup of pasta water and drain the rest.
Add the spaghetti to the pan with the guanciale and toss to combine. Remove the pan from heat.
Add the egg and cheese mixture and stir quickly. The residual heat will create a smooth, creamy sauce. Add a splash of pasta water if needed to loosen the sauce.
Finish with freshly ground black pepper and serve immediately.
Notes
Remove the pan from heat before adding the egg mixture to prevent scrambling.
Use pasta water to adjust the consistency of the sauce.
Pecorino Romano cheese gives the most authentic flavour.
Work quickly when combining everything to achieve a smooth emulsion.