What's the title and who's the author of old children's book?

It's the story of a little girl who wouldn't eat and wouldn't clean her room, so her mother sent her to live with her aunt. Her aunt told her there was a horribly mean witch that would come and punish them terribly if they did not finish their meals and clean their room, but she knew the little girl didn't want to eat, so she fed her on a tiny dish, and she helped her clean her room, I think. I'm fuzzy on that. But anyway, the aunt said she had to run down to the store or something, but to watch out for the witch, because she usually came to inspect when the aunt was out, and she did, and she was terrible and frightening, but since they had eaten their meals, cleaned up the dishes, and straightened the bedroom, she left disappointed. Every day or two, the aunt would give her a plate bigger than the last, until she was eating a full meal and happy to clean her room. I don't know if she ever found out that the witch was really her aunt or not. I heard this story about fifty years ago. My fifth grade teacher read it to us a chapter a day, and I've wanted to re-read it for a long time. Can anyone identify it?