This version is made by grinding basil, garlic, pine nuts, and coarse salt in a mortar, then working in cheeses, oil, and butter. Right before tossing, a little pasta water loosens the sauce so it coats evenly.

Ingredients
Equipment
Method
- Lightly crush the garlic to loosen the skin, then peel and discard the skin.
- Briefly soak and wash basil leaves in cold water, then pat them gently but thoroughly dry.
- Put basil, garlic, pine nuts, and coarse sea salt in a mortar. Grind with a rotary motion against the side of the mortar until a paste forms. Add both grated cheeses and grind them evenly into the mixture.
- Add olive oil in a very thin stream, beating it in with a wooden spoon. When incorporated, beat in the softened butter until evenly blended.
- When spooning over pasta, dilute the pesto slightly with 1 to 2 tablespoons of the hot pasta water.