Heat the oil in a saucepan or flameproof casserole dish over a medium heat and fry the onions for 8-10 mins until golden. Scatter in the garlic and chilli, season with salt and cook for 2 mins more. Stir through the squid and cook for another 10 mins until the squid has tightened up and any liquid has evaporated. Splash in the wine and bubble away for 5-6 mins, then tip in the tomatoes. Stir well, reduce the heat to low and simmer gently for 25-30 mins until the squid is tender and the sauce thick and rich. Once completely cooled, the ragu can be covered and chilled for up to two days or frozen for a month. Defrost completely in the fridge overnight and reheat over a low heat until bubbling before continuing with step two, below.

Cook the pasta in a large pan of boiling water for a minute less than pack instructions. Meanwhile, stir the clams or mussels into the ragu. Cover with a lid and cook over a medium heat for 6-8 mins, giving the pan an occasional shake until all the clams have opened – remove and discard any that remain closed after this time. Turn off the heat.

Drain the pasta, reserving a little of the cooking water. Stir the pasta into the ragu and warm everything through over a low heat for a minute, adding a small splash of the reserved water if the sauce needs to be loosened. Turn off the heat and add a drizzle of oil, the parsley leaves and lemon zest. Stir, then bring the pan to the table for serving alongside a separate bowl to collect the clam shells.