Can someone help me remember a title?

[Chuchincakes]

I once read a book when I was a kid by Roald Dahl but I can't for the life of me remember the title. I remember it was about a child who I think lived on a farm or something and someone made some kind of potion and all the chickens got really huge. I also seem to remember a mean grandma sitting in a rocking chair. Well, if someone can help me I'd really appreciate it!

 

[Ice]

The book you want is George's Marvelous Medicine

 

[Chuchincakes]

The book you want is George's Marvelous Medicine

Thanks, I really appreciate it!