Wipe the basil leaves carefully with paper towels or a clean cloth to remove any dirt. Discard the stems.

Classic Method: Place a few basil leaves in a mortar.

Add a clove of garlic and crush the leaves and garlic against the sides of the mortar using the pestle.

Add a few more leaves of basil and another garlic clove, and repeat the process.

Once you have crushed all of the basil and garlic, add the pine nuts.

Crush until the basil, garlic, and pine nuts are well blended.

Add a tablespoon of olive oil and combine with the ingredients in the mortar.

Then add the Pecorino Romano a little at a time, stirring with a wooden spoon.

Stir in some more oil, a tablespoon at a time until you have a thick, creamy sauce.

Blender Method: Place all of the ingredients in a blender.

Blend at high speed for 1 minute.

Lift the lid carefully and scrape the sides of the blender cup using a rubber spatula.

Check the consistency of the pesto, which should be thick and creamy.

Blend for a few more seconds if you think the pesto should be a bit thinner, but don't overdo it.