Searching for a fairytale . . .

Years ago, I remember reading a story in which a girl disguises herself as a man in order to fulfill a quest, in the course of which another girl falls in love with her.  At the end of the story, the heroine is granted one wish, which is to become a man indeed.  I thought it was "The Satin Surgeon," but I just re-read that story, and it so isn't.  Am I smoking the Andrew Lang crack pipe, or is there such a tale in the Fairy Books?

Please advise.  I'm supposed to be addressing a class on the subject of genre and fairy tale next Wednesday, and I'd love for them to read this story (supposing it exists outside of my fevered imagination) in preparation.