This is one version of a famous cake that originated in Austria and is modelled after the Mozartkugeln chocolate marzipan truffles. This is an elegant, elaborate cake that takes lots of time and some degree of skill to prepare, but is well worth the extra effort.Translated & adapted from "Kochen & Geniessen" magazine, directly from the German. If you are serving this to adults and want even more Mozartkugeln flavor -lightly brush the cooled cake layers with some Mozart Liqueur before stacking. In Germany, marzipan is often sold unsweetened in the baking aisle, in which case, you will need to add powdered sugar to it (which will absorb into the marzipan as you knead it). In the US, marzipan is often available already sweetened, in which case you can omit the powdered sugar, or add some to taste.