Active time: 45 min Start to finish: 4 hr

Makes about 2 quarts ice cream.

INGREDIENTS

  • for ice cream
  • 1cup roasted, shelled, and skinned chestnuts; see how to roast fresh chestnuts ; (1/2 lb in shell or 7 ozbottled whole)
  • 3cups whole milk
  • 1 1/3cups heavy cream
  • 6large egg yolks
  • 1 1/2cups packed darkbrown sugar
  • 1/4teaspoon salt
  • 1(4-inch) strip freshorange zest, removedwith a vegetable peeler
  • 1teaspoon vanilla
    for sauce
  • 1cup heavy cream
  • 6oz fine-quality bittersweet chocolate (not unsweetened), finely chopped (1 cup)
  • 2tablespoons unsalted butter
  • 3to 4 tablespoons grand marnier, or to tastespecial equipment: an instant-read thermometer and anice-cream maker

    DIRECTIONS

    Make ice cream:
    Finely chop chestnuts and cook with 1 1/4 cups milk at a bare simmer in a large heavy saucepan, uncovered, stirring occasionally, 15 minutes. Puréein a blender until smooth (use caution when blending hot liquids).


    Bring cream and remaining 1 3/4cups milk just to a simmer in heavy saucepan and remove from heat.


    Beat together yolks and brown sugar in a large bowl with an electric mixerat high speed until thick and pale and mixture forms a ribbon when beaters are lifted.

    Whisk 1/3 of hot cream mixture into yolk mixture to temper, then whisk yolk mixture into remaining cream mixture. 3Whisk in chestnut purée and salt, then add zest. Cook over moderately low heat, stirring constantly, just until mixture registers 170°F on an instant-read thermometer (do not boil).


    Immediately pour custard through a fine sieve into a clean metal bowl and stir in vanilla. Set bowl in a larger bowl of ice and cold water and cool custard, stirring occasionally. Chill, surface covered with waxed paper, until cold,at least 3 hours.

    Freeze custard in ice-cream maker, then transfer to an airtight container and put in freezerto harden.


    Make sauce:
    Bring cream just to a simmer in a heavy saucepan over moderate heat and remove from heat. Add chocolate and butter, whisking until smooth. Whisk in Grand Marnier.


    Serve ice cream with sauce.


    Cooks’ note:
    •Custard can be chilled up to 24 hours.