Traditionally pounded in a mortar and pestle, this intense sauce is quick work in a food processor. A little bit goes a long way, and it keeps well.
Chop the nuts, garlic, and salt in a food processor until fine. Add the basil and oil and process until smooth. Add the cheese and process to incorporate. Taste for salt.
Make Ahead Tips
Pesto freezes well for up to three months, but if you're planning to freeze it, omit the Parmesan, instead adding it to the thawed pesto just before using. To freeze, portion the pesto into ice cube trays or small plastic freezer bags so you can defrost only as much as you'll use at one time.
Parsley and walnut pesto: Make the basic recipe, substituting fresh parsley for the basil and walnuts for the pine nuts. For bigger flavor, lightly toast the walnuts first and add a bit of grated lemon zest to the sauce.
Cilantro and pumpkin seed pesto: Make the basic recipe, substituting cilantro for the basil, toasted pumpkin seeds for the pine nuts, and a neutral-tasting oil (grapeseed or vegetable) for the olive oil. Omit the cheese; add a bit more salt.