Heat up a small pan over medium heat, add the pine nuts and toast them until golden brown for 3-4 minutes (note 1)
in a food processor blend the pine nuts with the garlic
add the cheese and the basil leaves and about ⅓rd of the oil and blend again in short pulses (note 2)
slowly add more oil until the desired consistency is reached (note 3)
add salt and pepper to taste and keep covered in the fridge (note 4)
Notes
Note 1: Be careful to not leave the pan out of sight and keep stirring. The first 60-90 seconds it will look like nothing happens but then browning starts very quick and the nuts can burn super fast.This step is not mandatory but highly recommended. It will take the taste of the pesto to the next level. Note 2: Don´t blend it too long once the basil is added. Too much mixing can turn the basil bitterNote 3: The amount of oil depends on how fluid you like your pesto and what you want to use it for. Add a bit more for a pasta sauce and a bit less to use it as a spread or stuffing.Note 4: If you always keep the pesto covered with olive oil it will last very long because the oil acts like a cover and doesn't let any air touch the ingredients.