Combine the basil and garlic in the bowl of a food processor fitted with the s-blade. Pulse until coarsely chopped, about 15 1-second pulses.
Add the Parmesan and pulse a couple of times to combine.
With the food processor running, pour the oil through the feed tube and process until mixed, about 30 seconds. Stop the food processor, scrape down the sides, and process again until smooth, about 10 seconds more.
Season to taste with salt.
Notes
Storage and freezing--Store in a covered container in the refrigerator for up to 1 week, or freeze for up to 6 months.
Dietary--This nut-free pesto recipe is suitable for gluten-free and vegetarian diets.