Bring cream, milk and cinnamon to a simmer in saucepan. Remove from heat and whisk in chocolate until melted. Whisk together yolks, sugar and a pinch of kosher salt, and then whisk in the chocolate mixture. Strain through a fine mesh sieve into a bowl and allow to cool to room temperature.
Preheat oven to 300F degrees. Line a roasting pan with a folded kitchen towel and put 6 to 8 ramekins on towel. Divide cream custard among ramekins and add enough boiling hot water to pan to reach halfway up the side. Cover pan tightly with foil and poke some holes to allow steam to escape. Carefully place pan in oven and bake until custards are set around the edge, but slightly wobbly in the center – approximately 30 minutes.
Cool custards on rack uncovered about 1 hour, then chill at least 3 hours. Serve with whipped cream and orange zest or orange peel for decoration.