Clean, wash and cut the rhubarb into small pieces. For the dough, stir the fat and sugar until foamy. Stir in eggs bit by bit. Mix flour, baking powder and cinnamon. Alternately stir in flour mixture and milk.
Spread the dough on a greased tray. Spread rhubarb on top. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for about 20 minutes. In the meantime, mix marzipan, sugar and eggs to a smooth mixture for the griddle.
Pour into a piping bag with a small star-shaped spout and squirt onto the cake in a grid pattern. Sprinkle with almond flakes. Put into the oven again and bake at the same temperature for about 20 minutes.
Results in about 24 pieces.