It's sung by Amanada Marshall, she's one of my favorite Canadian singers. She does a nice variety of song of both silly and serious songs. Actually, one of my other favorite songs by her is something I think you would like too, it always makes me cry, but in a good way ^_~
http://www.youtube.com/watch?v=P_7wP8wK6PE

You really have to wonder what the writers were on when they were writing those episodes...especially the Wonderland episode. @_@

Anyway, thanks. ^_^