What was this book about kids in real-world Disney World populated by the scary witch

I remember, as a kid, having a book that was a story about two kids in the real-world Disney World, but that scary witch from Sleeping Beauty (Maleficent?) was running around in the park. There may have also been other “come to life” characters from Disney stories.

What was that book? Was it based on a cartoon or movie, or was it a standalone thing?