Serves 6 Active Time 25 min. Total Time 3 hrs.
3 cups whole milk
8 large egg yolks
2/3 cup sugar
1/4 cup cornstarch
1/4 teaspoon salt
2 tablespoons unsalted butter, softened
1 1/4 teaspoon vanilla
1. Heat milk in a heavy saucepan over moderate heat until hot but not boiling.
2. While milk heats, whisk together yolks, sugar, cornstarch, and salt in a heatproof bowl until smooth.
3. Gradually add 1 cup of hot milk to yolk mixture, whisking constantly. Transfer egg mixture back to saucepan and cook over moderately low heat, stirring constantly, until thickened and registers 170°F on thermometer, 8 to 12 minutes (do not boil).
4. Take off heat and stir in butter and vanilla. Chill custard, its surface covered with wax paper, until cold and thickened, at least 3 hours.