Very first chapter book

My daughter is 7 and just about ready to try her first chapter book. But anything above about 50 pages intimidates her. What's a good short, introductory chapter book for a beginning reader?

She really wants something funny. The longest book she's read so far was a collection of knock-knock jokes, and she read it three times before it was due back at the library. She also loved being read Captain Underpants, Wayside School, Charlie and the Chocolate Factory, and Matilda, although they are too long for her to read by herself.

Sci-fi and fantasy have not been hits. We only got about three chapters into The Lion, The Witch, And The Wardrobe. She took one look at Dealing With Dragons and said it didn't look interesting at all.