Explain that if you put butterflies inside the cake, then you'll have to have a big hole in it and there won't be enough cake to eat? Then buy some different colours of roll-out (fondant/sugarpaste) icing and a butterfly shaped cutter, and stick them on the outside, each guest can then take one home?
Squires Kitchen online shop are great for decorating stuff if you haven't anywhere local.


Squires Kitchen - Inspired by Food Online

__________________
Sarah

“Tell me one last thing,” said Harry. “Is this real? Or has this been happening inside my head?”
“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?”