You need
2 cups basil leaves
2-3 cloves garlic
1ml salt
125ml olive oil, good quality, extra virgin
125ml grated parmesan or pecorino cheese
125ml nuts. Traditionally pine nuts are used, but may be replaced with unsalted cashews, macadamias, or almonds
Roasted nuts give more flavour.
To prepare
Pick the leaves from the stems. Discard the flowers. Wash the leaves well. (I cut up the stems and flowers in the rinsing water and then pour that into the garden. Basil is an excellent insect repellent)
Place garlic, oil, salt and leaves in the food processor. Mill until a pâté consistency to the smoothness level that you prefer.
Add the nuts and mill until they have broken town to the size that you like.
Finally, add the cheese and mill for a few seconds.
Place in an airtight jar with a thin layer of oil on the surface. The surface exposed to air will turn brown, this is natural oxidation, but will not affect the flavour.