Slice guanciale into lardons and grate Pecorino Romano or Parmigiano Reggiano.
Toast black peppercorns in a dry pan until fragrant and crush in a mortar and pestle.
Add the guanciale to a pan and fry until the fat has rendered and become golden brown and crispy.
Drain out the fat to save for the sauce, which is a combination of egg yolks, the grated cheese and toasted peppercorns.
Give that a mix to make a paste before whisking in the cooled down guanciale fat.
Boil spaghetti in salted boiling water until al dente, making sure to save some of that starchy pasta water.
Place a big bowl over the pot of hot water to act as a double boiler, add the sauce mixture, cook spaghetti and crispy guanciale and stir, adding pasta water as necessary.
Plate it up with some more guanciale, grated cheese and black pepper.