Substituting fruit purees in baking
I just heard the best show on public radio on Saturday when I was driving around buying dirt, but that's another story. I wish I could credit the show, but I didn't catch the name. Anyway, here's what I learned.
You cannot substitute fruit purees (such as applesauce) for fat in a recipe when the recipe needs the fat for volume. So, if the recipe starts out with creaming the butter and sugar, for example, subbing's a no-go.
You can substitute fruit puree when the recipe calls for melted butter or oil. These are not used for volume. Do be aware, though, that it will make your recipe turn out more "cake-y." I just did it with my favorite brownie recipe yesterday and they weren't as dense, although still very good.
Good luck, and have fun experimenting!