- In a large pot of salted boiling water, cook the pasta until al dente. Set aside 250 ml (1 cup) of the cooking water. Drain the pasta and return to the pot.
- Meanwhile, in a large skillet, brown the pancetta and onion in the oil. Pour into the pot with the pasta and stir to combine.
- In a bowl, combine the eggs with 125 ml (½ cup) of the cooking water and the Parmesan cheese with a whisk. Generously season with salt and pepper. Pour over the pasta and toss to coat well.
- Reheat over low heat, stirring constantly, until the egg mixture begins to thicken and lose its gloss. Adjust the seasoning. Serve in soup bowls. If desired, form a little nest in the centre of the pasta and fill with an egg yolk. Sprinkle Parmesan cheese around the nest.