"Marshmallow fluff has to be the stuff of wizards." It's literally out of this world, in fact, since it was once sent into space. Watkins also praises its sandwich partner, peanut butter ...

Usually served on two slices of white bread, the sandwich consists of a thick layer of creamy peanut butter and a heavy serving of sticky Marshmallow Fluff. Over time, it has become one of the ...