Place a large pan of water over a high heat and add a good pinch of salt.
Bring to the boil and cook the spaghetti according to the packet instructions.
80 g spaghetti
Add the oil to a frying pan over a medium heat. When hot, add the pancetta/bacon and the onion and fry for about 10 minutes until the pancetta is cooked and the onion has softened.
65 g smoked pancetta, 1 tbsp extra-virgin olive oil, 1 small onion
Add the egg yolks to a small mixing bowl together with the grated parmesan.
2 yolks eggs, 30 g Parmesan
Whisk together until totally combined.
Once the pasta is cooked, drain over the sink retaining a mug of the pasta water.
Add the spaghetti to the pancetta and onion pan and toss well to coat the pasta.
Season with black pepper. The pancetta is salty so you probably wont need to add salt.
Remove from the heat and add the egg and parmesan mixture.
Constantly stir/toss to cover the spaghetti until it is fully coated. If the egg and cheese mix is too thick, add a little of the retained pasta water to thin.
Serve in warmed bowl immediately with a further grating of parmesan.