"Someday My Prince Will Come" is a song from Walt Disney's 1937 animated movie Snow White and the Seven Dwarfs.
It was written by Larry Morey (lyrics) & Frank Churchill (music), and performed by Adriana Caselotti (Snow White's voice in the movie).
The scout was casting the upcoming film and noted that a previous candidate had sounded like a 30-year-old, so was let go; Caselotti picked up the extension and recommended herself.
[1] Meanwhile, Frank Churchill was chosen as the film's composer, who was instructed by Walt Disney to write something "quaint" in order to "appeal more than the hot stuff".
The song was then briefly sung on the 1971 sitcom All in the Family by Edith Bunker in the episode "Archie's Weighty Problem".