My version of the iconic Choo Choo Train Cake, from the Women's Weekly Children's Birthday Cake Book, was going to be a fresh, fun take on the original. There'd be sprinkles and buttons and cookie wheels! Oh my! I'd replace the colored icing with luscious butter cream expertly covered in sprinkles, and the colored popcorn 'cargo' would instead be the fancy salted caramel variety. It was going to be a rainbow-colored spectacular. I already had my 'Best Mum Award' smug face on. I watched this tutorial many times.