The following recipe is super loose because it all depends on your flavour preferences:
In a food processor, stuff in the leaves from a bunch of basil and a big handful of spinach (you can use all basil if you prefer, I use a mixture because spinach is cheaper). Add a couple of cloves of minced garlic, a handful of raw cashews (almonds or pine nuts can also be used), a dash of salt and the juice of one lemon. Pulse and scrap down the sides. It should be a bitty mixture. Turn the food processor on and drizzle olive oil in through the top. The amount of oil really depends on your preference of consistency – I don’t add too much if I’m intending on freezing it (I usually make a big batch and then freeze it in little containers).