L.C.
How about making her-her own b-day cup cake ,instead of a big piece.
Maybe a carrot cake my kids love that. She will probably make more of a mess with whatever you give her and not really eat it,well thats what ended up happening with my three kids. Good luck.
P.s you know they have jello recipes too!!!!!!!! Nothing really healthy when it comes to cake, hey maybe banana cream pie. Lol