When I click on the cake, there is a dialogue about trying to find out what kind of cake it is, but nothing more. When I click on the books, or try to use the picture on the books, it mentions cookbooks, but no pictures of cake come up when I do that. So it looks like the issue is that I'm not getting the images of cakes from the cookbooks to click on?
OK, so to confirm, you've spoken to the father about the cookbooks, then when looking at the books you were told to check the photo (this is supposed to happen if you haven't already found out what you need to). Did you right-click on the photo in inventory, to look at it and click on the cake from there?