Pesto means “paste” and can be made of nearly anything, but I love nut based pestos. For this one the star isn’t a soft herb, like basil or parsley. Instead it’s pure pistachio nuts with a few garlic cloves, some salt and parmesan and enough olive oil to give me the texture I want. Nut pestos can be assertive and the texture quite thick, so it’s important to “lighten” them before tossing with pasta with just a bit of the pasta cooking water. I wait until the pasta is boiling and has given the water the gift of a bit of starch. Then I start adding the cooking water one tablespoon at a time to the pesto until I reach a texture that will just nap the pasta without overwhelming it or any additional ingredients I’m adding.
Don’t skimp on the quality of oil you use. I had a bottle of Cappezzana Oil from the famed Tuscan estate and put it to good use. This is exactly what these high end oils are good for.