Put the orange juice in a small saucepan and reduce it to about halfway. Add the whipped cream and sugar and bring to the boil once, then remove the saucepan from the stove.
Roughly chop the chocolate, add to the cream mixture and stir until the chocolate has melted. Pour in the liqueur and stir everything well.
Fill the liqueur into bottles and store in a cold place. Shake well before serving.