For the chocolate mousse, whisk Qimiq until smooth (preferably with a hand mixer) and refine with rum, powdered sugar and possibly vanilla sugar and/or lemon zest.
Melt the chocolate in the microwave or over a bain-marie while whipping the whipped cream. Slowly whisk the whipped cream and liquid chocolate into the Qimiq mixture. Let the chocolate mousse cool in the refrigerator for at least 1 hour.