I use nutritional yeast to make a cheese sauce. It tastes pretty good
(in our family's opinion). I served cauliflower "au gratin" at a holiday
dinner, and none of our guests even suspected they were eating a
non-dairy sauce. My 11-yr-old daughter has to pass over so many food
items in her daily life that I make it a point to plan a holiday menu
that includes all safe foods for her. I have found a lot of recipes for
non-dairy cheese sauces, etc. on vegan web sites.

Joanne in NJ