In a pot, boil some water, and add oil and salt in it.
Add pasta and cook it for 6-8 minutes on high flame till al dente.
Save some pasta water for further use, and sieve away the rest. Also drizzle some oil and black pepper on the pasta and let it rest.
This step is optional. Roast the pistachios in a pan for 30 seconds, roughly crush them, and keep them aside.
You can check out how to whip up the sauce in the previous post.
In the same pot as used for boiling, add the sauce and thin it up by adding the pasta water saved before. Stir it continuously till you get a consistent sauce, add the cooked pasta, salt, pepper, and mix well.
Finish it off by sprinkling crushed pistachios and chopped parsley over the pasta and your pistachio pesto pasta is ready to be served.