Heat together cream, chocolate, and sugar in a medium saucepan over medium heat, stirring constantly, until chocolate is melted and smooth.

Pour a little of the chocolate mixture into beaten egg yolks and vanilla in a medium bowl; mix until smooth. Pour back into the saucepan with remaining chocolate mixture. Heat gently, stirring constantly, until custard thickens slightly.

Spoon custard into small dessert bowls and garnish with whipped cream.