Here's What You'll Need
basil leaves, walnut, garlic clove, lemon zest, olive oil, parmigiano reggiano
Place the basil, toasted walnuts, garlic, lemon zest, and lemon juice in a food processor. Secure the lid, the pulse until very finely chopped.
With the motor running, slowly drizzle in the olive oil, as needed. You want the sauce to be liquidy as the cheese will help to thicken the sauce.
Transfer the sauce to a bowl, then stir in grated Parmesan cheese. Taste and adjust seasoning, as needed.