The pasta is enhanced by a topping of pangrattato, etymology of which is from pane (bread) and grattato (grated). I read somewhere that this was the poor Italian man's substitute for parmesan cheese, which was a more expensive commodity. Pangrattato is made from dried mushroom, breadcrumbs, rosemary and garlic. In Jamie's recipe, he uses dried porcini mushrooms, but since that is very expensive here in Singapore, I just use dried shitake mushrooms and it's fine.
The dish doesn't use as much pasta as other pasta dishes because half of it is made of leeks.