In a small bowl add milk and sprinkle the gelatin on top.
In a medium saucepan mix ¾ cups of cream with sugar. Simmer until the sugar is dissolved. Add chocolate and cocoa until melted/dissolved. Stir in the remainder of the cream until warm.
Remove from heat and add the gelatin mixture and orange zest or vanilla. Whisk until smooth.
Pour the mixture through a fine mesh strainer into a large bowl.
Butter 6 ramekins lightly. Divide the mixture between the ramekins using a ladle. Cover with plastic wrap and refrigerate for 4 hours up to overnight.
If you wish to unmold, run a knife around the edge and immerse in a warm water bath for a few minutes. Invert on a plate and serve with a little orange zest on top.
Serves 6