"Birthday cake made of fruit" No. Not a cake. Just a big slice of watermelon with some pretty fruit on it. And if you try to serve this to me as my birthday cake, clearly you are asking to be ridiculed for the rest of your natural life.
Bake and ice a round cake, making sure its shorter than a Kit-Kat bar. Break 4 packs of Kit-Kats into two bar segments. Surround the cake with the Kit-Kats and then tie with a ribbon. Fill the top with a large bag of M's.