Reserve two tablespoons of the nuts, then put the remainder in a food processor with the mint, parsley and garlic. Blitz for ten seconds, then scrape down the bowl. Add a little salt and half the oil, then blitz for five more seconds.
Add about two-thirds of the cheese and the remaining oil and blitz for another five seconds. Pour into a large warm bowl and taste for seasoning.
Cook the linguine in lightly salted water until al dente. Once done, take 50ml (just over three tablespoons) of the cooking water and add it to the pesto.
Drain the pasta in a colander and add to the pesto. Toss it all together thoroughly and taste for seasoning, before serving in warmed bowls with the remaining parmesan and pistachios sprinkled on top.