This has been bugging me for a long time! I can't remember all the details, but there's a scene in the cartoon where the children eat enchanted candy and they start to turn into "brick people" that stack up to make a wall... I think there might be a princess in a tower at some point. No one believes this movie exists!

Sounds like repeat offender Unico: In the Magic Island (http://www.anime-planet.com/anime/unico-in-the-island-of-magic). A movie which is one of my bitterest enemies.

UNICOOO!

There must be quite a few on the same theme I read somewhere about a "Black Caldron" with the same theme as "unico".