Im pretty sure its the Womans Weekly, at the checkout at target there is a new cookbook, Gluten and allergy free cooking, there is some in there. Also the easiest way is in the health food row. You can buy allergy free packet cake mixes.
You might also be able to make you own cake out of icecream, SoGood make yummy flavours, strawberry, chocolate, vanilla. Icecream cakes go down a treat with our family. If you decorate it with lots of lollies it looks pretty too.