Stracciatella Ice Cream

1 cup (240ml) whole milk
¾ cup (150g) sugar
2 cups (480ml) heavy cream, divided
1 vanilla bean, halved lengthwise
6 large egg yolks
¾ teaspoon pure vanilla extract
140g (5 oz) fine-quality bittersweet chocolate (no more than 60% cacao if marked), chopped

Combine milk, sugar, and 1 cup (240ml) cream in a 1- to 2-quart heavy saucepan. With tip of a knife, scrape seeds from vanilla bean into mixture, then add pod. Bring mixture just to a boil, whisking until sugar has dissolved, then remove from heat. Cover and let stand 30 minutes.

Reheat cream mixture over medium heat, stirring, until hot. Whisk yolks in a medium bowl, then add half of hot cream mixture in a slow stream, whisking constantly, then pour yolk mixture into remaining cream mixture in saucepan, whisking. Cook custard over medium-low heat, stirring constantly with a wooden spoon, until custard is thick enough to coat back of spoon and registers 76 to 79ºC/170 to 175ºF on an instant-read thermometer (do not let boil).

Strain custard through a fine-mesh sieve into a metal bowl. Stir in vanilla and remaining cup cream, then return vanilla pod to mixture. Chill, uncovered, until cool, then chill, covered, at least 6 hours. Remove vanilla pod and freeze custard in ice cream maker.

While ice cream is freezing, melt chocolate in clean metal bowl set over a saucepan of barely simmering water, stirring frequently, then transfer to a 1-cup glass measure. When ice cream has finished churning, carefully pour chocolate in a slow stream directly onto ice cream as it churns and continue to churn 30 seconds (chocolate will harden in streaks). Transfer ice cream to an airtight container and put in freezer until firm, at least 4 hours.

Makes about 1 quart (950ml)