What nut is traditionally used in pesto alla genovese?

The nut traditionally used in pesto alla genovese is the pine nut.

Pesto alla genovese is the classic green sauce associated with Genoa in Liguria, northwestern Italy. Its traditional ingredients include Genovese basil, garlic, extra-virgin olive oil, hard cheeses such as Parmesan and pecorino, and pine nuts. The ingredients were historically crushed together in a marble mortar with a wooden pestle, a method reflected in the sauce’s name: pesto comes from a word meaning “to pound” or “crush.”

Pine nuts give the sauce a rich, buttery texture and a subtle resinous flavor. They also help create the creamy paste that coats pasta. Traditional recipes may use European pine nuts, sometimes lightly toasted, although many modern versions vary in technique and proportions.

Cashews, almonds, and walnuts can replace pine nuts in contemporary or budget-friendly recipes, especially for people with allergies or when pine nuts are expensive. Those substitutions may still produce a tasty pesto, but they are not the canonical nut in traditional pesto alla genovese.