"Carbonel, the King of the Cats"

This is one of my favorite childhood books, written by Barbara Sleigh, about a little girl in London who finds a talking black cat. The cat (Carbonel, who is the King of the cats), has accidentally become the minion of a witch and the book is about the adventures the cat and little girl have un-doing the spell that binds Carbonel to the witch and regaining his kingdom from a dangerous imposter. This is a book for older children (and young-at-heart adults) who love a good story and is out-of-print and difficult to find, but very fun and quirky. It has a couple of sequels, but the first one is the best. While not specifically a Halloween book, there is magic and traditional witch lore, with brooms, cauldrons, and a peaked witch's hat.