Step 1: Begin by lightly toasting the pine nuts in a dry skillet over medium heat for 2-3 minutes until golden and fragrant. Set aside to cool.
Step 2: In a food processor, combine the toasted pine nuts, garlic cloves, and sea salt. Pulse until the mixture is coarsely ground.
Step 3: Add the fresh basil leaves and black pepper to the processor. Pulse in short bursts until the basil is finely chopped but not yet a paste.
Step 4: With the motor running on low, slowly drizzle in the extra virgin olive oil. This helps create a stable emulsion for a creamy basil pesto recipe texture.
Step 5: Transfer the mixture to a bowl and stir in the grated Parmigiano-Reggiano and Pecorino Romano by hand. Stir in the lemon juice if using.
Step 6: Taste and adjust seasoning. Use immediately or store in an airtight container with a thin layer of olive oil on top.