Heat 1 cup whipping cream in 2-quart saucepan over medium heat until hot. Gradually stir at least half of the hot whipping cream into egg yolk mixture; stir back into hot cream in saucepan. Cook over low heat about 5 minutes, stirring constantly, until mixture thickens (do not boil). Stir in chocolate until melted. Cover and refrigerate about 2 hours, stirring occasionally, just until chilled.