Method

• 1.
  Remove skin from guanciale (reserving it for the stock), then cut guanciale into 5mm dice. Bring 400ml of the stock to the boil in a medium saucepan over high heat and add the reserved guanciale skin, along with any parmesan rinds you may have, then reduce heat to low and simmer gently for 30 minutes. You don’t want the stock to reduce too much, so cook it over very low heat. You should end up with about 1 cup (250ml) – make up this amount with more stock, if needed.
• 2.
  Put the diced guanciale into a frypan over very low heat and cook slowly until all the fat is rendered and it becomes very crispy – this could take up to 15 minutes. In the meantime, use a whisk or stick blender to mix the egg yolks and pecorino into the warm stock mixture until well combined. Once the guanciale is done, use a slotted spoon to remove, and set aside. Strain the rendered fat into the egg yolk mixture and whisk or blend again, then pour back into pan and keep warm.
• 3.
  Cook spaghetti in boiling salted water according to packet instructions, until al dente. Drain pasta and add to pan, then toss until sauce thickens and coats pasta. Grind in a generous amount of black pepper, add crisp guanciale and toss another couple of times – you may need to adjust consistency with a little more stock.
• 4.
  Divide between warmed bowls and serve with more grated pecorino.