All it was was a card with an equation. The answer was a certain room in Hogwarts. Enclosed was a request to solve the equation, then go to the room.
Matt was in there covered in ice cream toppings and waiting.<
I figured you'd want something more brutal than chocolate.
So Ofdensen got him sugar skulls and a digital recorder.
In the end, she was too shy to give the cake to him herself, so she just owled it.