Prepare the Lebkuchen Layer Place the honey, sugar and butter in a saucepan and heat and stir until sugar is dissolved. Remove from heat and cool until lukewarm.
Mix egg yolk with water and baker's ammonia, then add to honey mixture and combine well.
Stir in flour, ground almonds and potash (or baking powder*). Dough will be stiff.
Pat into a 7 by 7 inch square, between 1/4 and 1/2 inch thick on parchment paper. Straighten the edges by pushing them with a knife.
Bake at 350°F (175°C) for about 25 minutes, or until set but not browned.
Cool, then cut the square in half horizontally, like a layer cake, using a serrated knife.
Prepare the Marzipan Layer Place the almond paste and powdered sugar in a bowl. Cut the two together with a pastry dough cutter.
Add the rum or water and work into a smooth paste.
Roll the paste between wax paper (use powdered sugar to help it not stick, if necessary) out to fit the Lebkuchen.
Assemble the Cookies Lay out the bottom layer of Lebkuchen. You can brush it with sugar water or more rum, if you wish, to make the squares a little softer.
Brush half the marmalade or jam over the bottom layer. Place the marzipan on top of the jam.
Brush the other half of the jam on the underside of the top layer and then put the two layers together like a sandwich. Press together tightly.
Use a knife with a serrated edge to cut the large, square sandwich into one-inch squares, using a sawing motion for clean edges.
Coat the Dominosteine with Chocolate Melt the chocolate coating (also known as Almond Bark in the US) or couverture according to package directions. Use shortening to thin, if necessary.
Dip each cookie in the chocolate, rolling to coat all sides.
Lay out on waxed paper to dry.
Store in layers separated by wax paper. These cookies will keep at room temperature for several weeks.
*You may substitute 1/2 tsp. baking powder for the ammonium carbonate and 3/4 tsp. baking soda for the potassium carbonate.
If you like gingerbread, take a look at this list of German gingerbread recipes .