In a saucepan over medium-high heat, combine the orange zest, milk, cream, and cinnamon stick. Heat until small bubbles appear at the edge of the pan, then remove from the heat. Let stand for 1 hour to develop the flavors.

In a small, heavy saucepan over low heat, combine 1 cup (8 oz/250 g) of the sugar and the water. Stir until the sugar dissolves. Bring to a boil over high heat. Boil, without stirring, until the liquid is golden brown, 6-8 minutes. Carefully pour the hot syrup into the bottoms of eight 1-cup (8-fl oz/250-ml) ramekins or custard cups, immediately tilting and swirling the dishes to coat the bottoms and sides with the caramel. Place the dishes in a large baking pan. Set aside.

 Preheat an oven to 325°F (165°C).

Strain the cream mixture through a sieve into a clean saucepan. Warm over medium-high heat until tiny bubbles appear along the edge of the pan. (Do not allow to boil.) Meanwhile, in a bowl, whisk together the whole eggs, egg yolks and the remaining 1 cup (8 oz/250 g) sugar until frothy. Gradually beat in the hot cream mixture, a little at a time. Stir in the vanilla, and then the wine, if using. Strain the mixture through a sieve into the caramel-lined dishes, dividing it evenly.

Pour hot water into the baking pan to reach halfway up the sides of the custard cups. Cover the pan with foil and place in the oven. Bake until a knife inserted in the center of a custard comes out clean, about 30 minutes.

Remove the baking pan from the oven and remove the dishes from the pan. Let cool for 30 minutes, then cover and refrigerate until well chilled.

Just before serving, carefully run a knife around the inside edge of each custard and invert into individual shallow dessert bowls. Pour any extra caramel in the dishes over the custards and serve.