If nuts are raw, you can toast in the oven (350 F) on a rimmed baking sheet for 5-7 minutes. Toss the nuts halfway through. Transfer to a food processor and let cool.
Add Parmesan, garlic, lemon juice, and salt to the nuts and pulse in a food processor until finely ground (about 1 minute).
Add basil to the food processor.
While running the motor, slowly add the olive oil in a steady stream and continue processing until the pesto is smooth.
Taste and add more salt if needed.
Note: You can substitute walnuts with shelled pistachios for a unique and delicious flavor.
Should you make pesto up to 24 hours before using, place in a jar and top with ½ inch oil to prevent the mixture from browning (due to oxidation), and store in the refrigerator.
To serve with pasta, select 12 oz of a dried pasta, choosing a variety with ridges or spirals which are perfect for holding this delicious sauce. Prepare according to the package instructions.