Remove any tough basil stems and make sure the leaves are thoroughly dry. Add the basil, pine nuts, garlic, kosher salt, and optional black pepper to a food processor, then pulse several times until finely chopped.

With the food processor running, slowly pour in the extra-virgin olive oil. Stop occasionally to scrape down the sides, pulsing only until the mixture looks finely blended and spoonable.

Add the finely grated Parmesan and pulse just until incorporated. Taste the pesto and adjust with more salt, pepper, olive oil, or the optional lemon juice.

Use the pesto immediately, or cover and refrigerate it for later. For pasta, loosen the sauce with a little reserved pasta water before tossing.