Ziti spezzati nduja e ricotta (ziti with ’nduja and salted ricotta)

Method

1. Put 2 tbsp of the oil in a saucepan over a low-medium heat, then add the onion. Cook for 15 minutes until very soft, then tip in the passata and season with a pinch of salt. Leave to very gently simmer for 1 hour or until the sauce is thick, rich and glossy (add a splash of water if it starts to catch).
2. Once cooked, add the remaining oil to another saucepan over a low-medium heat. Add the garlic, sizzle until golden, then stir in the basil. Immediately pour the oil into the tomato sauce, stir, then pour the sauce into a sieve set over a bowl. Use the back of a spoon to push the smooth sauce through the sieve – you should end up with around 250g in total.
3. Bring a large pan of salted water to the boil. In the same saucepan you used to infuse the oil, add the ’nduja and put over a medium heat. Cook until the ’nduja melts, then pour in the tomato sauce and two thirds of the cheese. Stir and  leave to gently simmer while you boil the pasta for a few minutes less than it states on the packet instructions (or until al dente).
4. Drain the pasta, reserving a cup of cooking water, then add it to the sauce. Stir vigorously, adding splashes of the pasta water as needed to loosen the sauce. Divide the pasta among bowls, then serve with the remaining cheese, some fresh basil leaves and a final drizzle of olive oil.