Toast the pine nuts in a dry pan over a medium heat until golden and nutty, tossing occasionally, around 4-5 minutes.
Put the toasted pine nuts, basil, garlic and half the parmesan plus 2 tbsp. of the oil in the food processor and pulse to a paste.
Scrape the paste into a bowl and slowly trickle the rest of the oil in, stir to combine.
Stir in the rest of the parmesan, seating to taste and a little more oil if too thick.
Scrape into a Kilner jar or clean jam jar, cover with a layer of oil (so it doesn't discolour) and chill.