Gently wash the basil in cold water and pat dry with a towel. Crush a clove of garlic in a mortar (or food processor) and add some basil, and then a sprinkle of salt. Repeat this process until all the basil and garlic are added. Add the pine nuts and gently crush them into the mixture. Next, add the cheese. When the cheese is mixed in, slowly drizzle in the olive oil and mix together. At this point, the pesto is ready to use.
Prepare the Clams:
Remove any clams that are broken, or which do not close immediately if tapped. Soak the clams in a large bowl of cool water for at least 20 minutes in order to purge any remaining sand.
(Note: Purging freshly caught clams should be done in sea water for at least 12 hours. For supermarket bought clams, 20 minutes should suffice)
Cook the Clams:
In a large skillet over medium heat, saute the garlic in olive oil until golden. Remove the garlic with a slotted spoon. Add the clams and cover. Cook for about 3-5 minutes or until the shells open (discarding any clam with a shell that does not open).