Yellow cake with fondant icing. Sliced the cake in half at an angle, then twisted the top around 180 degrees to get the tilt. Originally, this was going to be on top of a larger rectangular base cake, but we didn't have dowels etc and were afraid it would be too heavy, plus didn't want the headache of having to disassemble it before we served it. We put it in the fridge since the event was still two days away -- made the fondant a little bit shiny, but nobody seemed to care.