To make the chocolate mousse, melt the chocolate in a glass bowl over simmering water.
Whip the cream until soft peaks form.
Mix the two together to form a marble effect. Be careful not to overmix them.
Put into a tall glass.
For the oranges, in a medium saucepan heat the butter and the sugar together to form a caramel.
Add the oranges and continue to cook for two minutes.
Place in a small glass dish and serve with the chocolate mousse.