This is from "Captain" on another forum.

An old boy scout recipe.
Take an orange and cut the top off as you would for a boiled egg. Scoop out and eat the inside of the orange. Half fill with chocolate cake mix, put the top back on the orange and wrap it in foil. Place it in the hot coals for about 10 mins. Remove, unwrap, take the top of the orange and voila, lovely orange flavoured chocolate cake. It keeps the kids busy around the camp fire and makes them eat a piece of fruit otherwise they will miss out on their chocolate cake dessert.

Cheers,
xina.