Place chocolate in a bowl.
In a saucepan, mix 2 cups (500 ml) of cream, Grand Marnier and orange rind.
Bring to a boil.
Soak the gelatine leaves in cold water for 1 minute.
Melt the gelatin in the hot mixture.
Pour the mixture through a sieve, onto the chocolate chips.
Whisk just until smooth.
Pour the mixture into cocktail glasses.
Refrigerate for 12 hours or until firm.
Whip the remaining cup of cream (250 ml), adding vanilla and sugar, until firm.
Prepare the orange supreme: remove peel as well as the skin from each slice.
Serve the Panna Cotta cold with whipped cream and orange.
