With a sharp knife, slit the sausage skins lengthways and pop all the meat out. Using wet hands, roll little balls of sausage meat about the size of large marbles and set aside.
Heat a large frying pan and add a good splash of olive oil. Gently fry the sausage balls until golden brown all over, then add the pancetta and continue cooking for a couple of minutes, until it's golden. While this is cooking, bring a pan of salted water to the boil, add the linguine, and cook according to the packet instructions.
In a large bowl, whip up the egg yolks, cream, half the Parmesan, the lemon zest and parsley. When the pasta is cooked, drain it in a colander, reserving a little of the cooking water, and immediately toss it quickly with the egg mixture back in the pasta pan. Add the hot sausage meatballs and toss everything together. The egg will cook delicately from the heat of the linguine, just enough for it to thicken and not scramble. The sauce should be smooth and silky. If the pasta becomes a little claggy, add a few spoonfuls of the reserved cooking water to loosen it slightly. Sprinkle over the rest of the Parmesan, season, if necessary, with the salt and pepper, and drizzle with extra virgin olive oil. Eat immediately!