Looking for the REAL Bill Knapp's Au Gratin Potatoes recipe?

I am looking for the REAL recipe! I am positive Bill Knapp's did NOT use Velveeta cheese, as I have already tried those online recipes, and they were not the same. Too mild. Does anyone remember how to actually make this recipe? I've read that Old English Cheddar was used, but not the exact way to put it together. I'd really appreciate a former Bill Knapp's cook replying to the request.