Note: This recipe has been amended as of Jan. 21, 2013, to address a customer comment about lack of strong vanilla flavor. Thanks, as always, for your feedback.
1) Freeze the work bowl of an ice cream maker according to the manufacturer's instructions.
2) Pour the milk and cream into a saucepan set over medium-high heat, and bring it just to a boil. Add the vanilla, remove from the heat, and let sit in the saucepan at room temperature for 30 minutes.
3) In another saucepan, beat together the egg yolks, sugar, and xanthan gum until light and airy. Stir the warm milk into the egg yolk mixture.
4) Heat the yolk/milk mixture (custard) over low heat, stirring with a heatproof spatula until it thickens somewhat; it'll be approaching the thickness of heavy cream and will register between 170°F and 180°F on a digital thermometer.
5) Remove the pan from the heat and let the custard cool to room temperature, stirring occasionally to prevent a skin from forming. Refrigerate for at least 2 hours, or overnight.
6) Transfer the mixture to an ice cream maker. Freeze according to the manufacturer's instructions.
7) If you prefer soft, creamy (soft-serve) ice cream, serve immediately. For a firmer consistency, transfer the ice cream to an airtight container and freeze for about 2 hours.
Yield: about 1 quart.