My teenage sister collects rubber duckies and asked that I make her a duck cake for her birthday. The cake didn't rise all the way and she had more friends invited than I had originally anticipated, so I improvised by making a 1-layer 13x9 chocolate cake and made it look like the duck was swimming on a pond. The duck is yellow cake with buttercream and sheet cake is store-bought vanilla frosting with buttercream accents.