To cook the pasta
Cook the pasta in salted water until just al dente. Set aside approx. 100 ml of the cooking water. Drain the pasta.
Puree the parsley with the reserved cooking water and all the other ingredients up to and including the oil. Mix in the chives.
Heat the oil in a large non-stick frying pan. Stir fry the mushrooms for approx. 4 mins., add the onion, cook for approx. 1 min., add the lemon juice. Pour in the cream, simmer for approx. 4 mins., season with salt. Add the pasta, gently heat through and serve with the pesto.