1 1/4 cups whole milk
3 large egg yolks
1/3 cup sugar
4 oz (120g) bittersweet chocolate, finely chopped
1/2 tsp pure vanilla extract
Bring the milk just to a simmer in a saucepan over medium heat. Do not boil. Whisk the yolks and sugar together in a heatproof bowl until pale yellow and thick. Slowly whisk in the warm milk. Return the mixture to the saucepan. Cook over low heat, stirring constantly with a wooden spoon, until the custard coats the spoon (an instant-read thermometer will read 185F (85C)). Remove from the heat. Add the chocolate and vanilla. Let stand until the chocolate softens, then melts. Strain through a sieve into a bowl. Serve warm, or let cool, cover, and refrigerate at least 1 hour, until chilled. Variation: Chocolate-orange Custard Stir the grated zest of 1 orange to the strained sauce.