This cake is perfect for last minute requests, as you can knock it up in seconds. Simply cook two circular cakes, and cover both in light blue fondant. Draw a curved line down the middle of a sheet of green fondant and cut across it, making two pieces of hilly green fondant. Attach to the blue fondant. Next, use square and circle fondant cutters to make wheels and train parts in various colors of fondant. White circles can be easily overlapped to create smoke! Glue on using jam, and cut two white fondant strips. Glue diagonally so that they create a square, and use a cake pen to write a birthday message before gluing to the top of the cake using a lollipop stick. Perfect.