That sounds delicious! Do you happen to know the nutritional info by any chance?
Also, I've found this cheese substitute called "Veggie Shreds" that are cheddar cheese flavored (they're in the vegetarian section of the grocery where tofu and stuff is sold). Anyway, they are really good and melt much better than fat free cheese. They aren't fat free (70 cal, 4g fat, 0g sat fat for 1/4 c) but another option. I think they are soy based - so lactose free if you need that.
Hethyr
SW: 348/351; CW: 339; GW: 300 (starting small, ultimate gw is 170); 1st mini goal: 335