Using a mortar and pestle, crush the garlic with several pinches of salt. Add the walnuts and crush into a paste.

Add the basil leaves gradually, using a circular motion to crush and tear the leaves against the wall of the mortar. After all the basil is incorporated, add the cheese and olive oil in a thin stream and stir with the mortar to incorporate. As you mix, remember these words from Nuova Marmotecnica, the makers of a fine selection of marble mortars and pestles: “[It is] ideal to marry all the ingredients without overwhelming them.” Buon appetito!