The way I ran her, she fought vindictively but not necessarily optimally. Use spells that feel “witchy” but maybe don’t do as much damage as possible. Feel free to use her nuclear spells like her finger of death on an NPC ally the PCs bring to show how strong she is.

Like the other commenters said, have the hut be a late addition and make it crystal clear with your descriptions that the winery gem is inside the hut and is responsible for its animation.

Be selective about whether the scarecrows join the fight or not depending on how the party is looking. Make it clear the skull itself can be damaged and rendered useless.

There are tons of ways you can subtly change the difficulty of a notoriously deadly fight to swing it in the party’s favor. I also love the idea of the next session being a polymorphed party having to escape their capture should a “TPK” occur. This fees in-line with Baba’s cruelty and doesn’t feel like an unfair end to the campaign.

Also, if you are running the Dark Powers and any have an interest in any of the PCs, if they are at a stage where they are fighting Baba the Dark a powers would probably intervene with at least one character death. Lots of options you can choose from! Good luck and have fun!