Nutritional Yeast is pretty amazing stuff. It's high in protein, low in fat and has lots of B-vitamins and minerals. You can buy it in bulk at most health food stores or larger grocery stores. It's a form of the same yeast, saccharomyces cerevisiae, found in bread, beer and sourdough. It is grown on molasses and pasteurized to kill the yeast before being sold.
I like the idea of the recipe for Melty Nutritional Yeast 'Cheese' Sauce because, besides the nutritional yeast, it calls for ingredients most people would have readily available - cornstarch, flour, salt, garlic powder, water, mustard and vegetable oil.
This is a recipe from the The Nutritional Yeast Cookbook