I made the SpongeBob Birthday Cake by using a basic sponge recipe, 5 eggs, 315g self raising flour, caster sugar and margarine and 155g plain flour and using a 8″x10″ cake tin.
I covered the cake in butter icing then covered it in yellow sugar paste, adding a white strip of sugar paste for the shirt and brown for the trousers on top of the yellow. All the features were also made from sugar paste, circle cutters to create the green spots and eyes, Sausage shapes for arms and legs etc. I used strips of licorice for the eyelashes.
It was important to just build up each of the features gradually to give the cake a realistic look especially the mouth area.