"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.
What fun, sweet treat? Fill these waffle cones full of fresh fruit for a summer snack, or picnic dessert. Healthy bonus: they are full of anti-oxidants! (Use red and blue fruits, maybe mini marshallows too?