The baking supplies sound like a really good idea! Asking the teacher of the baking class is probably a really safe way to go for a recommendation. Other possible ideas might include:
--a very nice glass pedestal cake plate (depending on your W's taste you could buy traditional Wedgwood china, Waterford crystal, or funkier Venetian glass) --an out of town trip to a baking class somewhere nice like New Orleans. She might see it as a chance to get away from childcare and have some "me" time??
The second idea may be too much, but I'm throwing it out there for consideration.
Finally, what I think would be a REALLY nice touch.....something that would REALLY surprise her....would be to include as a separate gift box a selection of small quantities of several unique spices and flavorings that a baker might use. I'm thinking vanilla beans, stick cinnamon (there are several types), real vanilla extract (there are several types), roasted cacao nibs, dried pansies, saffron, lavender sugar........you get the idea. If you go to a really nice cooking store they will have a big selection of these spices and they will give you recommendations about the top sellers. When your W opens the gift you will be able to tell her all about your trip to the store (LL quality time) and how you tasted or smelled each of the spices before making your selections. If you have never done anything like this before I think your W will be REALLY surprised. She will likely smell each as she opens it. The pungent fragrances will add to her enjoyment. Over the next few weeks she will be thinking about what she could bake to use the most unusual or fragrant spices and probably ask you for your feedback about what items you would most enjoy eating.