Vanilla Bean Custard Ice Cream

1 cup milk
2/3 cup granulated sugar
2 vanilla beans, cut in half lengthwise
9 large egg yolks (at room temperature)
2 cups heavy cream
Combine milk, sugar and vanilla beans in the top of a double boiler and heat over barely simmering water. Lightly beat the yolks.

When milk mixture is almost to the point of boiling, pour a little into the yolks to warm them. Stir and add a bit more hot milk. Pour warmed yolks into the milk in a slow, steady stream, stirring constantly. Continue to cook, stirring constantly, over hot, not boiling, water until mixture coats the spoon.
Press a sheet of wax paper or plastic wrap directly onto the surface of the custard and allow to cool to room temperature.
Add cream to the custard and refrigerate for several hours.
Just before freezing, remove vanilla beans and scrape their seeds into the mixture. Stir and pour into an ice cream maker and freeze according to manufacturer's instructions. Makes 1 quart.