Fifi's Black Cat Halloween Cake is elegant and entirely edible. The cake (and the body of the cat) consists of a cocoa genoise with a center layer of chestnut buttercream; the icing is whipped ganache. Other decorations are made from colored "plastic" chocolate -- dark chocolate for the face and paws, and white chocolate for the pumpkins.
This cake design is modeled after one for which plastic decorations can be purchased, at Verna's Cake Decorations.