That is the spooky scary cake Duff Goldman and Charm City Cakes created for the New York premiere of Harry Potter and the Deathly Hallows, Part 2. It's the wizarding school Hogwarts, half destroyed by magic or whatever. Ron Weasley himself, actor Rupert Grint, cut the first slice. Below, a photo with the lighting effects turned off.
[Photo: Charm City Cakes]