Well, youth can be relative! Remember she spends all of act one as a decrepit hag... so... it all depends when she the spell took effect. And I'm SURE you're not implying that mid 30s or even 40s is a disqualifying age to which "youth and beauty" can be returned! Don't forget Bernadette was nearly 40. 40!
But I think there are many more exciting options for the Witch, The Baker's Wife I find harder to cast or get excited about the casting of (sincere apologies to Emily Blunt, Stephanie J Block, Kelly O'Malley, Sutton Foster).
