Thank you all for your suggestions! We ended up making the graveyard cake, inspired by the Martha Stewart tombstone cupcakes. We used a chocolate cake recipe from Christopher Kimball and also his ganache recipe, though my friend remembers the cookbook names and I don't...sorry! We used Martha's chocolate shortbread for the gravestones, found on her site, as well as her royal icing. The cake was sooo moist and delicious!
And...best of all, we won! Even better, the prize was a cookbook--Kimball's Dessert Bible. Totally perfect, since that's where the recipe mostly came from!
Thanks to all of your for your suggestions!
I'm trying to figure out how to post a link to the photo...such a thing goes beyond my tech-know how!