For the gingerbread slices, preheat the oven to 160 °C hot air. Line a baking tray with baking paper. Beat the egg with a little warm water until foamy.
Mix in sugar, honey, cocoa powder, lemon and orange zest, gingerbread spice and additionally some cinnamon and cloves. Add 1 dash of rum and mix vigorously.
Mix flour with baking powder and fold in alternately with milk. The dough should be viscous! Spread the dough on a baking tray and bake for about 20-30 minutes.
Let cool, sprinkle with powdered sugar or similar and cut into cubes.