In a large soup pot, add garlic, celery, parsley branches, sage, thyme, the bay leaf and saffron. Cover with 2 quarts of water, bring to a boil and simmer for 30-45 minutes, or until the garlic cloves are soft. (While the soup is cooking prepare the pasta in a separate pot if using). Smash the garlic with the back of a spoon, allowing it to disintegrate into the broth.
Next strain the liquid into another pot and add one cup each of watercress, kale and spinach. When the greens start to wilt, add pre-cooked pasta shells. Season with sea salt to taste.
To serve, finish with fresh chopped parsley, Parmesan cheese and fresh ground pepper if desired.