cups heavy cream
vanilla bean, split in ½ lengthwise
large egg yolks
Combine the cream, milk, sugar, and vanilla seeds and bean in a medium heavy saucepan and bring to a gentle boil over medium heat. Remove from the heat. Beat the egg yolks in a medium bowl until frothy and lemon colored, about 2 minutes. Whisk 1 cup of the hot cream into the egg yolks in a slow, steady stream. Gradually add the egg mixture to the hot cream, whisking constantly. Cook over medium-low heat, stirring, occasionally, until the mixture thickens enough to coat the back of a spoon, about 5 minutes. Remove from the heat and strain through a fine-mesh strainer into a clean bowl. Cover with plastic wrap, pressing it directly against the surface of the mixture to keep a skin from forming. Refrigerate until well chilled, about 2 hours. Pour mixture into an ice cream maker and freeze according to the manufacturer's instructions. Transfer to an airtight container and freeze until ready to serve.