For the chocolate sauce, coarsely chop the couverture, heat in a saucepan with the milk until the chocolate has melted. Add the whipped cream and cognac.
Pour the mixture through the iSi funnel & sieve into a 0.5 L iSi device, screw on an iSi cream capsule and shake vigorously.
Keep the iSi device warm at max. 75 °C in the bain-marie or in a water bath.