I used a straight roasting tin and made two sponge cakes. I placed them on top of each other to cut them straight so they are exactly the same size. I then stuck them together by filling it with raspberry jam and frosting. I cut the top of the cake flat and covered it in frosting.
To make the characters I used coloring in pages which I searched for on the internet, printed them off and cut out all individual colored areas and used this as a template. I used ready roll icing to make the characters and food coloring to achieve the correct colors. You may have to play around with this for a while but spend the time on it as it really will be worth it.
I then cut out the areas from the template and put them back together like a jigsaw puzzle. I used a food dye pen to go around the characters to give them a detailed effect. Tip is to make sure all characters are the same size so they do not look too odd on the cake. I used strawberry laces for the balloon string and used a food dye pen to personalize the names on the balloon.