The Frauenhuber is a famous old cafe and this is its even more famous “Haustorte.” It’s not as sweet as it looks, and it’s quite delicious. The Frauenhuber is on the ground floor of a building on Himmelpfortgasse. Wolfgang gave concerts on the next floor up, in what used to be Jahn’s Coffeehouse. In MOZART’S LAST ARIA Nannerl meets Prince Lichnowsky at Jahn’s. They eat something a little like this Haustorte…Well, who could resist? After all, a mystery must include some sins.