It's actually Dirt Cake! Yes, an edible and delicious creation from the mind of a friend of Martha Stewart. I saw this years ago on her show and have made it several times. It is easy and feeds a crowd. You can find the recipe here, http//www.marthastewart.com/259619/janes-dirt-cake. For kids of all ages, you can also add gummy worms to the dirt.
For the record, this is definitely the best kind of dirt to dig into!