1. Lightly fry the onion in the oil and then add the garlic and zucchini. Fry for a short time and then add half the stock and simmer slowly for about 40 minutes adding more stock when necessary so that a sauce consistency can be obtained.
  2. Blend the resulting mixture and set the sauce aside.
  3. Cook pasta according to packet directions, strain and set aside
  4. In a heavy based pan, place the butter and allow it to melt with low to medium heat. Add the slices of fontina cheese and when they start to melt add some of the zucchini sauce. Mix and add the cooked pasta.
  5. Add more zucchini sauce and the parmesan cheese, toss and serve topped with the chopped basil.