Gently wash the basil leaves, paying attention not to crunch them.
Lay the basil leaves onto kitchen paper and let them to dry. DO NOT press or pat the leaves with kitchen paper but leave them to dry naturally.
Add the basil leaves into the mortar.
Add the pine nuts into the mortar.
Add the garlic (roughly chopped) into the mortar.
Add the salt into the mortar.
Start working with the pestle, pressing and rotating it. Keep going for a few minutes until all the ingredients are finely ground.
The more you work the mixture with the pestle the better.
After a few minutes working with the pestle, add the cheese and...
...continue to work the mixture with the pestle until you have an evenly distributed light green colour.
Now, add the olive oil.
Use a small spoon to stir so that the olive oil is evenly distributed.
This is the final result. Now you can coat spaghetti with it or spread it onto bread slices.