Bring a large pan of salted water to the boil, then cook the pasta following pack instructions, about 9 mins. Around 3 mins before the pasta is cooked, add the peas.

Meanwhile, heat the olive oil in a frying pan over a medium heat and fry the onion for 5 mins until soft but not golden. Add the ham, double cream, lemon juice and parmesan, then season and mix well. Remove from the heat.

Drain the pasta and peas (keeping a mugful of the cooking water) and return them to the pan. Tip in the creamy ham mixture and stir everything together to combine. If the mixture seems a little dry, add some of the reserved cooking water to loosen it a little. Serve with extra parmesan on top, if you like.