Melt the nougat in a water bath and remove from the stove. Add the marzipan mixture to the nougat and stir with a fork. It then dissolves very well.
Beat the fat, sugar and salt until frothy. Stir in the eggs one at a time. Mix the flour, starch, cinnamon and baking powder and sieve onto the egg-fat mixture. Add the milk and stir everything briefly.
Preheat the oven to 180 ° C. Grease and flour the baking pan.
Remove 2/3 of the dough and fill in the baking pan. Stir in the remaining third of the cocoa, plum jam and the nougat and marzipan mixture. Then pour onto the light-colored dough and fold in a spiral.
Bake for 55 minutes. Let cool for half an hour and then turn out of the mold. Then dust with powdered sugar.