Add the basil, pine nuts, parmesan cheese, garlic, and lemon juice to the bowl of a food processor.
Pulse until the basil is finely chopped.
With the food processor on low speed, slowly drizzle in the olive oil. Once all of the oil has been added, allow the food processor to run for an additional 10-15 seconds to fully incorporate the oil. Scrape down the sides of the bowl as necessary.
Season with salt and pepper to taste. Store the pesto in an airtight container in the fridge for up to four days.
You can substitute up to one cup of basil with another green vegetable-- carrot tops and spinach are great pesto add-ins.
The pine nuts can be substituted for walnuts.
Basil pesto freezes very well. Freeze in small portions for up to a year.