Hotel Sacher where we had Sachertorte, caffe mit schlag (real whipped cream)!
The cake consists of two layers of dense, not overly sweet chocolate dough with a thin layer of apricot jam in the middle and dark chocolate icing with shreds of chocolate on the top and sides. It is traditionally served with whipped cream (Standard German: Schlagsahne, Austrian German: Schlagobers), as most Viennese consider the Sachertorte too "dry" to be eaten on its own.
The trademark for the "Original Sachertorte" was registered by the Hotel Sacher, which was built in 1876 by the son of Franz Sacher. The recipe is a well-kept secret