Could you start a direct conversation with her? What I'm getting from your post is that you'd rather have a relationship than FWB, and if that's accurate, I'd probably avoid the FWB because it just gets ... confusing and messy when one person really wants a relationship and the other doesn't (and ALL my fwb situations turned up that way sooner or later, but that could just be me!). Her buying you cake makes me wonder if she might be into you too...