Step 1: Prepare Your Basil. Gently wash your fresh basil leaves and pat them thoroughly dry with paper towels or use a salad spinner. Place the dry basil leaves in the bowl of your food processor.
Step 2: Toast the Pine Nuts (Optional, but Recommended). In a dry skillet over medium-low heat, gently toast the pine nuts for 3-5 minutes, shaking the pan frequently, until they are lightly golden and fragrant. Remove from heat and let cool slightly. Add the toasted pine nuts to the food processor with the basil.
Step 3: Add Garlic and Cheese. Peel and roughly chop the garlic cloves. Add them to the food processor along with the grated Parmigiano-Reggiano. Pulse the mixture several times until the basil, nuts, garlic, and cheese are finely chopped and well combined. Scrape down the sides of the bowl as needed.
Step 4: Slowly Drizzle in Olive Oil. With the food processor running on low, slowly drizzle in the extra virgin olive oil through the feed tube. Process until the mixture is smooth and creamy. You might need to pause and scrape down the sides a few times to ensure all ingredients are fully emulsified.
Step 5: Season and Adjust. Once your pesto has reached the desired consistency, stop the food processor. Taste the pesto and season with salt and black pepper as needed. Pulse a few more times to incorporate the seasonings.
Step 6: Storage. Transfer your freshly made pesto to an airtight container. To prevent oxidation, pour a thin layer of olive oil over the surface before sealing. It will keep in the refrigerator for up to a week. For longer storage, freeze in ice cube trays, then transfer to a freezer-safe bag for up to 6 months.