Put the sprigs of mint, Doppelkorn, white rock candy, lemon and orange peel into a bottle. Let it steep for 14 days, shaking or stirring occasionally. Over time, the liquid first turns green, then green-olive.
After 14 days, remove the sprigs of mint, strain the liqueur, mix with the coffee cream and fill into bottles. The liqueur is now almost white again (if you want a deep green, you can help with food coloring).
Store in the refrigerator, serve well chilled / on ice and dusted with cocoa.