1. To make the ice cream base: Pour the milk and cream into a saucepan set over medium-high heat and bring the mixture to a boil. Add the vanilla, remove from the heat, and let sit in the saucepan for 30 minutes.

  2. In a separate saucepan, beat together the egg yolks, sugar, and xanthan gum, until light and airy. Stir the warm milk and cream into the egg yolk mixture.

  3. Place the pan over low heat and cook the mixture, stirring, until it thickens slightly; it will register between 170°F and 180°F when measured with a digital thermometer. Remove the pan from the heat and let the custard cool to room temperature, stirring occasionally to prevent a skin from forming. Cover and refrigerate for at least 2 hours, or overnight.

  4. To make the marshmallow swirl: Place the egg whites and cream of tartar in the bowl of an electric mixer fitted with a whisk attachment and set aside.

  5. In a medium saucepan, combine the water, sugar, and corn syrup or honey. Stir to combine. Insert a candy thermometer and heat the mixture over medium-high heat. Don't stir the mixture as it cooks or it will become grainy.

  6. When the sugar syrup begins to form large bubbles and the thermometer reads about 225°F, begin to beat the egg whites to soft peaks (this should take about 3 to 4 minutes). By the time the egg whites are done, the sugar syrup should be at 240°F. Remove the syrup from the heat and, with the mixer running at medium-low speed, carefully pour it down the side of the bowl into the whites in a thin, steady stream.

  7. The whites will deflate a little at first, but continue to beat and the mixture will begin to expand. Whip for 7 to 8 minutes, until the spread is very thick and glossy. Add the vanilla and whip for 1 more minute. Pour the spread into an airtight container and store at room temperature.

  8. To finish the ice cream: Transfer the chilled custard to an ice cream maker and freeze according to the manufacturer's instructions. Once the ice cream begins to thicken but is still soft, fold 1 1/2 cups of the marshmallow spread into the ice cream, leaving discernible streaks throughout.

  9. Place the finished ice cream in a container with a tight-fitting lid and freeze for up to 2 months.

Tips from our Bakers

  • Mixing in some chopped salted almonds and melted milk chocolate gives you a rocky road ice cream clone.