2 leeks, finely chopped
1 medium potato, peeled and chopped
2 fresh sage leaves
1 small Savoy cabbage, finely chopped
450g/1lb pizzoccheri pasta (buckwheat flat ribbon pasta, available in some supermarkets or specialist delis) or dried tagliatelle
salt and freshly ground black pepper
125g/4oz butter
175g/6oz fontina cheese, chopped
100g/3陆oz bitto cheese or parmesan, grated