Remove the toughest parts of the stems from the basil, chop the greens. Peel, crush and chop the garlic.
Grate the parmesan on a fine grater, lightly fry the nuts in a dry frying pan over medium heat.
Place the basil with garlic and a pinch of salt in a mortar or blender and begin to grind, gradually adding oil in small portions.
Then add the nuts and grind the resulting mixture again, pouring in all the remaining oil.
Add the grated Parmesan to the pesto, season with salt and pepper. Store pesto in a sterilized jar in the refrigerator for up to a week.