In a large saucepan heat milk just to simmering. Meanwhile, if using vanilla beans, split beans lengthwise. Scrape out seeds. Remove milk from heat; add beans and seeds. Let stand, covered, for 10 minutes.
Add chocolate to milk mixture; return to low heat, stirring or whisking until chocolate is melted and milk mixture is hot. Whisk in liqueur and (if using) vanilla and honey. Serve immediately. Makes 4 servings.