1. Prepare an ice-water bath. Whisk yolks and 2 tablespoons sugar in a medium bowl. Bring cream, milk, salt, and remaining 2 tablespoons sugar to a simmer in a medium saucepan. Pour a third of hot cream mixture into yolk mixture, whisking until combined. Pour yolk mixture into pan with hot cream. Cook over medium heat, stirring, until mixture coats the back of a spoon, 6 to 7 minutes.

2. Place chocolate in a large heatproof bowl. Pour hot mixture over chocolate. Whisk until chocolate melts and mixture is smooth. Strain through a sieve into a medium bowl, then set in ice-water bath, stirring often, until cold. Press a piece of plastic wrap directly on surface of chocolate cream, cover, and refrigerate for up to 3 days.