Put a pot of water onto boil for the pasta. Add salt once the water starts to boil and bring to the boil again.
Put the pistachios into a bowl of boiling water for 3 minutes , drain them and wipe them with a cloth to remove most of the skin covering them.
Put the pistachios in a blender or food processor, add the grated cheese and 2 tablespoon of extra virgin olive oil.
As you start to blend/pulse add the rest of the extra virgin olive oil until you get a dense pesto. Add salt and pepper to taste.
Cook the pasta al dente according to the instructions on the packet. Save a cup of the pasta cooking water and drain the pasta and return it to the pan.
Add some of the pasta cooking water to the pesto to make it a little more liquidy and creamier.
Then add the pistachio pesto to the pasta and mix together well.
Serve immediately with extra grated cheese as required.