Looking for a kids fantasy book with a young boy main character who lives with his aunt and uncle by the woods

Its set in some undisclosed time in the past with a woodcutter or something coming to town and the kid befriending him and either following him into the woods or just going with him. Then they meet some weird hermit man/creature who lives in a treehouse, the man ends up being Hansel from Hansel and Gretel I think and he's trying to find out what happened to his sister all those years ago.there's an evil sorcerer or wizard I think that they are fighting by the end of the book. Its been bugging me forever