Heat the oil in a medium heavy saucepan and cook the onion over a moderate heat for 5 minutes until beginning to soften Stir in the garlic, fennel seeds and rosemary and cook for a further minute.
Add the sausagemeat to the pan and gently cook for 1-2 minutes, breaking up the meat with a wooden spoon. Add the passata, season and simmer , uncovered, for 10-15 minutes until thickened.
Meanwhile bring a large pan of water to the boil and cook the pappardelle according to packet instructions until al dente. Drain, reserving a ladleful of water, and return the pasta to the pan.
Ladle the sauce into the pan with the pasta and reserved water. Gently toss together, then served sprinkled with parmesan and basil.