Thomas Jefferson’s Ice Cream

2 quarts heavy cream
6 large egg yolks
1 vanilla bean
1 cup sugar

Bring heavy cream and vanilla bean to a simmer in a heavy-bottomed saucepan over medium-low heat, stirring frequently, until fragrant, about five minutes. Whisk egg yolks in bowl until smooth. Whisk sugar into eggs until thick. Slowly beat 1 cup of hot cream into egg mixture. Gradually stir egg-and-cream mixture into saucepan of hot cream. Stir constantly, until mixture is thick enough to coat the back of the spoon, about five minutes. Strain mixture into a bowl through a double layer of cheesecloth; remove vanilla bean. Stir until slightly cooled.
Refrigerate until chilled, at least an hour or overnight.

Freeze in an ice-cream machine, or in the freezer, until set but slightly soft.  Spoon ice cream into a three-quart mold, or several smaller molds, running a spatula through the ice cream and tapping the mold firmly to remove air bubbles. If using molds, cover and freeze for two to four hours. Dislodge molded ice cream by dipping mold briefly into hot water. Run knife around the top edge to separate ice cream from mold. Invert mold over serving dish and gently lift from ice cream. (If not molded, simply serve in small scoops.)