If you are using whole salsiccia sausages, start by slitting the casings open and scraping out the meat. Chop it roughly or crumble it between your fingers.
Heat a frying pan over a medium heat and brown the sausagemeat in a splash of oil for just under 5 minutes. Meanwhile, put the pasta on to cook and cook it to just under al dente, following the packet instructions.
Add the shallot and garlic to the pan, sprinkle over a few chilli flakes and keep frying until the shallot is soft and translucent.
Pour in the water, add the stock cube and the cream, and let the sauce simmer while the pasta finishes cooking.
Stir the parmesan into the sauce together with the lemon zest, and season to taste with freshly squeezed lemon juice, salt and freshly ground pepper.
Toss the pasta, peas and chives into the sauce and let it simmer until the pasta is al dente and the sauce clings to the pasta. Adjust the consistency with a little pasta water if needed.
Serve with extra parmesan and chives, if you like.