Step 1: In a food processor, combine the fresh basil leaves, pine nuts, garlic cloves, and salt. Pulse several times until the mixture is coarsely chopped. Scrape down the sides of the bowl as needed to ensure even processing.
Step 2: With the food processor running on a low setting, slowly drizzle in half of the extra virgin olive oil through the feed tube. Continue to process until the ingredients form a thick, coarse paste.
Step 3: Add the freshly grated Parmesan cheese to the food processor. Pulse a few more times until the cheese is just incorporated into the basil mixture. Be careful not to over-process at this stage, as it can make the pesto bitter.
Step 4: Continue to slowly drizzle in the remaining extra virgin olive oil while the food processor is running, until the pesto reaches your desired consistency. You can make it smoother or leave it slightly chunkier, according to your preference. If desired, add a teaspoon of fresh lemon juice to brighten the flavors.
Step 5: Taste the homemade pesto and adjust the seasoning with more salt if necessary. Transfer the pesto to an airtight container. For optimal freshness and to prevent browning, pour a thin layer of olive oil over the surface before sealing. This homemade pesto recipe can be stored in the refrigerator for up to one week or frozen for several months.