1. Bring the milk and vanilla bean to a simmer in a heavy-bottomed medium saucepan over medium-low heat. Add the chocolate, let stand for a few minutes, then stir until the chocolate is melted. Cover and let stand 15 minutes. Remove the vanilla bean and, using the tip of a small knife, scrape the seeds from the pod back into the milk. Rinse the vanilla bean and reserve for another use, if desired.

2. Whisk together the egg yolks and sugar in a large bowl until the mixture becomes thick and pale. Gradually whisk in the warm milk mixture, the pour into the saucepan. Cook over low heat, stirring constantly with a wooden spoon, until the mixture coats the spoon (an instant-read thermometer will read 185°F/85°C). Do not boil. Strain through a wire sieve into a bowl. Cool completely, stirring often. Cover and refrigerate at least 2 hours, until thoroughly chilled. Stir the cream into the chilled custard.

3. Pour into the container of an ice cream machine. Freeze according to the manufacturer's instructions. Stir in the white chocolate chips. Transfer into an airtight freezerproof container and freeze for at least 2 hours. Scoop into bowls and serve.