Old post, so I don't know if you ever figured it out, but I'm pretty sure the different images titled "cheesecake" with the Shadowed Curios owner are for if you've gotten her to the different weight stages and ask for the cheesecake at that point; IE, the one simply called Gothcheesecake is if you ask for it before you've tricked her, 2 is after using the amulet on her, 3 is after using the weight gain potion, 4 is after the fairy uses her magic on Nicole. I haven't actually tested this hypothesis yet, but it seems to me that's what the difference cheescake images for Nicole are.