I thought smash cake was something different? I thought it was a pinata cake, aww have one in a cake book, and better homes and gardens have one too (from their show, so I think it will be on their site).
Smash cakes are a shape (dome, cupcake, whatever) made from chocolate with lollies hidden underneath.

Some people also call those small cakes they give babies to "play with" (usually for photos) smash cakes, but I've always know smash cakes as the what I mentioned above.

Also if you google smash cake the first page that comes up is the dome chocolate kind!