The day before, quarter plums and soak in port wine.
The next day grease a square springform pan (24 x 24 cm) and dust with flour. Preheat the oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Mix 350 g flour, baking powder, brown sugar, 1 pinch of salt and gingerbread spice.
Heat 200 g butter, dark and light syrup in a pot until the butter has melted. Pour the butter and syrup mixture into the flour mixture while stirring constantly and mix to a smooth dough.
Stir in the eggs one by one.
Put the dough into the mould and smooth it down. Bake in a hot oven for 30-40 minutes. Remove from the oven and leave to cool for about 1 hour.
Drain port plums well. Roll out the marzipan on a work surface sprinkled with icing sugar to a thickness of about 2 mm. Cut out 80 circles (approx. 5 cm Ø each), kneading the remains again and again, roll out again and cut out.
Place 1 plum quarter on each circle and wrap with the marzipan.
Remove the cake from the mould. If necessary, cut the surface straight with a knife. Cut the cake into cubes of about 2.5 x 2.5 cm. Coarsely chop the couverture and the fat and melt together in a hot water bath.
Put 1 small blob of chocolate coating on each dough cube and place 1 marzipan plum on each. Cover the dominoes with the remaining chocolate coating and allow to dry well.