i've been experimenting w/ these and have yet to come up w/ a definitive recipe for what i like, but it so happens that what i like is a combination of two recipes (i had half of one recipe left over and added it to the same amount of a new recipe).

the first recipe is simply the "cheese" sauce from the macdougall maximum weight loss book. (i won't post it here, but if anyone wants it, post me privately.) i found this sauce to be rather tart in flavor and lurid in color. So next i tried a recipe for vegan mozzarrella cheese (can't remember where i found this; i've modified it slightly):

Place all ingredients in a food processor or blender, and process until completely smooth. Pour into a small saucepan and cook over medium heat, stirring constantly, until smooth and thick.

this is very tasty, but the tahini adds fat and too much of a "hummus" flavor. But when i mixed in half of the macdougall recipe, both recipes were transformed! the macdougall's flavor is much improved, and the color and fat content of the vegan mozzie recipe are both far more acceptable. Next time i make it, i'll figure out how to combine both recipes into one procedure. In the meantime, if you're looking for a thick, gooey, cheesy topping, try the vegan mozzie recipe (you could probably reduce the tahini to the vanishing point, but even in trace amounts, it provides an essential "cheesy" flavor) or experiment w/ these two recipes on your own!