I have a very limited baking repertoire. I make chocolate cakes. Sometimes I put chocolate icing on top, and sometimes, when requested to put a picture on top, I make royal icing and decorate. And that's it. It's worked fine until now, when DD2 has announced that she wants a plain sponge cake with a picture on the top. How do I do this? I am ok with simple instructions but do not have a recipe for a plain sponge cake (looks sadly at very successful chocolate cake recipe).