As rivalries go, this one is up there with Coke vs. Pepsi. Which of these two cultural institutions’ pastry chefs make the best version of Vienna’s famous Sacher torte? The Hotel Sacher is a historic property and, by legal right, has been recognized as the original home of the classic dessert. But a few blocks away on posh Kohlmarkt street, just steps from the Hofburg Palace, the pastry shop Demel proudly still carries the official title of royal confectioner. Both houses ship this spongy chocolate cake, covered with chocolate icing and layered with apricot jam, all over the world. But nothing beats tasting the sweet treat right there in old Vienna.