Combine 6 tablespoons of the superfine sugar with the egg yolks in a large mixer bowl. Set aside.

Place 1 cup heavy cream and the remaining 6 tablespoons superfine sugar in a heavy-bottomed saucepan. Bring to a boil. Turn off the heat and set a timer for 10 minutes. Immediately place the bowl containing the egg yolk mixture on top of the pot with the cream mixture to cover. Whisk the yolk mixture until the sugar dissolves, and then remove the mixing bowl from over the pot. Cover the pot with a lid for the remainder of the 10 minutes. With an electric mixer, beat the yolk mixture until it is pale and thick and forms a ribbon when it drops from the beaters.

While the egg yolks are beating, heat the wine until hot (ideally, if you have a candy thermometer, to 140 degrees). Remove from the heat and set aside.

Bring the cream mixture back to a boil, stirring constantly. Remove from the heat and pour a small amount of the cream into the bowl with the egg yolk mixture, whisking constantly as the hot liquid is added. Gradually pour in the rest of the cream mixture and the wine, whisking until well blended.

Pour the entire mixture back into the saucepan, place over medium-low heat, and cook, stirring constantly with a wooden spoon, until the mixture thickens. Do not let the mixture come to a boil or it will curdle. (If you have a thermometer, cook the cream until it registers 180 to 185 degrees, no more.) Immediately remove from the heat and continue stirring for a minute or two. Pour this ice cream base into a bowl and chill for at least an hour and preferably overnight, stirring occasionally.

When the cream mixture is thoroughly chilled, pour it into an ice cream maker and proceed according to the manufacturer's instructions.

Serve immediately, garnished with berries and mint leaves, if desired. Or transfer from the ice cream maker to a freezer container. Although the ice cream will keep a month or so, the flavors diminish slightly. It is better to serve it within 2 to 3 days if it's for a special occasion.