Fletcher and Zenobia by Edward Gorey is a rarity in that he wrote the book but didn't illustrate it. Instead, Victoria Chess did the artwork — but still in a style that looks Gorey-ish to me.

Fletcher's a cat who has decided to live up in the branches of a large tree. Zenobia is a doll who has become stuck up there under extraordinary circumstances. Together they have parties and adventures, including eating too much ice cream with a giant caterpillar.

Although the book is out of print, a number of libraries still have a copy. If you're interested in reading it, I suggest starting there. There is also a sequel, Fletcher and Zenobia Save the Circus. ( )