Ms. Endive put flarshmallows in Mungs air conditioner as seen in a flashback in "The Hot Date".
Gazpacho's mother's favorite flarshmallow is the lucky boweevil.
Oddly, in Shinzel and the Lead Farfel, Chowder said 'marshmallow" instead of flashmallow. Also in The Hot Date, Mung said "shrashmallows". Another food based on marshmallows happens to be called Harshmallows. They never made it into the TV series, though. It's likely that there is more than one way to say "marshmallows" in Chowder (TV Series).