Wash the arugula in cold water and spin dry in a salad spinner (optional, you can just drain it well if you don't have a salad spinner).
Add all the ingredients, except the olive oil, to a food processor bowl. Pulse until a thick paste forms (scrape the ingredients from the sides of the bowl from time to time).
Add the olive oil and pulse the sauce at the lowest speed until well combined or whisk in the olive oil by hand.
Season to taste with salt and pepper. You can also add more olive oil if you want a thinner consistency of your pesto.
Enjoy!
Notes
Ingredient notes:
arugula - arugula tastes a little bit bitter and peppery so make sure to make this pesto if you really like it, if its taste is too strong for you, you can add half arugula and half basil leaves
pistachios - I think this recipe works best with pistachios (salted and roasted) but if you don't have them on hand you can easily substitute them with cashews or almonds
parmesan cheese - use just parmesan or a mix of parmesan and pecorino (this is an aged sheep's cheese similar to parmesan but made with sheep milk), I have also once added a mix of parmesan and gruyere and it was also delicious
you could also add some red pepper flakes.
You will need about 9 oz (255g) spaghetti for 1 1/2 cups pesto.
Calories = whole recipe. This is only an estimate!