Smash up half of the pine nuts to a paste, then put it into a big heatproof bowl with the rest of the whole pine nuts, the lemon juice and zest, the finely chopped parsley and the extra virgin olive oil. Stir and add the Parmesan and pecorino. What you should have now is a reasonably thick sauce, which you should think of more as a dressing, so taste it and think about how the different flavours are coming through. I want you to balance the flavours so you end up with something quite zingy because, as the sauce heats up and the cheese melts, the flavour of the lemon will calm down a lot. Season with some freshly ground black pepper. Taste it and if you think you haven’t got the balance right, simply add a little more oil and Parmesan.
Put a large pot of salted water on to boil for your pasta. Sit the sauce bowl on top of the pan while the water’s heating up – this will take the chill out of the sauce and warm it through slightly. When the water starts to boil, remove the bowl and add your pasta to the water. Cook it according to the packet instructions then drain in a colander, reserving a little of the cooking water. Toss the pasta with the sauce and a little of the reserved cooking water to help loosen it up a bit. The heat from the pasta will melt the cheese, allowing all the lovely sauce to coat it. If you find the sauce is too thick then add a little more water. It’s not supposed to be claggy, thick and miserable, but incredibly silky, fresh and fragrant. Have one last taste to balance the flavours, and serve with a little extra Parmesan shaved over the top and a sprinkle of parsley leaves. Eat immediately.