In the Night Kitchen
Written and illustrated by Maurice Sendak

Sendak's hero Mickey falls through the dark into the Night Kitchen where three fat bakers are making the morning cake. So begins an intoxicating dream fantasy, described by the artist himself as 'a fantasy ten feet deep in reality'.

I'm not sure why it was banned, but possibly for nudity. The little boy, Mickey, is naked for part of the book, just as many little children are at that age!