It's probably a mis-translation from German. "Knack" is a german word that describes a specific sound - I'm not sure there is a precise English translation. The

It's probably a mis-translation from German. "Knack" is a german word that describes a specific sound - I'm not sure there is a precise English translation. The dictionary offers "click" or "snap" as a translation, "crack" would be another similar word. I assume that in this case "Knack" refers to the bite of the chocolate and describes a hard/brittle chocolate.