Preheat oven to 375°. Cream the butter and sugar with an electric mixer until fluffy. Add 1 egg at a time; beat for 1 minute before adding the next 1 to the mix. Then mix in the apfelkraut or rübenkraut. Set aside. Mix the flour, salt, cinnamon, ground cloves and cocoa powder together (if using baking powder, add it into the flour mixture now). Sift the flour mixture into a different bowl. Stir half the flour mixture into the egg mixture. Stir in the dissolved ammonium carbonate, the rest of the flour mixture, the finely grated chocolate and the hazelnuts. Stir everything until well combined. The batter will be quite sticky. Butter a 9- by 13-inch baking pan and line it with parchment paper. Spread the batter evenly on the lined baking pan, and bake in the oven for 20–22 minutes 
until a toothpick inserted in the center comes out clean.

While baking, make the glaze by mixing the powdered sugar and water. When the Berliner Brot is finished baking, let it cool a bit, then brush the glaze on while the Brot is still warm. Cool to lukewarm, then cut into 2- by 3-inch bars.

Tip: You can also put a little rum or rum flavor into the batter mix or add some finely chopped candied lemon peel or orange peel (available at grocery stores around the holidays).

This is an old-fashioned gingerbread recipe my German Oma used to bake for Christmas. Berliner Brot, often translated to “Berlin Christmas bread” in English, is lightly sweet and perfectly spicy with a hint of cocoa and just the right amount of hazelnut crunch. The dessert keeps well in an airtight tin, with cut pieces separated by wax or parchment paper. The flavor improves with age, so wait a couple of days before diving in.

This recipe calls for apfelkraut or rübenkraut and ammonium carbonate. Apfelkraut is German for apple butter and can be found at most grocery stores, if it’s not already in your pantry. You can find rübenkraut (beet syrup) and ammonium carbonate at a specialty store like Himmel Haus in Elkhart, IN, the German section of your local grocery store or online.