Bring a large pot of water to the boil with the salt.Add pasta and cook for the length of time per the packet.

Just before draining, scoop out 1 cup of of the pasta cooking water.Drain pasta in a colander, leave it for a minute.

Transfer pasta to a bowl (do not use pasta cooking pot, too hot).Add pesto and 1/4 cup of pasta water. Toss to coat pasta in pesto, adding more water if required to make pasta silky and saucy, rather than dry and sticky.

Taste, add more salt and pepper if desired.Serve immediately, garnished with fresh parmesan.