Heat milk in a small pan over moderate heat until it comes to a boil.
In a blender or food processor combine egg, 2 tablespoons of sugar, a pinch of salt, semisweet chips and liqueur, using the low setting. Pour in boiling hot half-n-half in a slow steady stream. (The hot milk will cook the egg and melt the chocolate.) Process or blend for 1 minute, until smooth.
Spoon into 4 small champagne glasses, teacups or ramekins and chill.
When ready to serve, whisk whipping cream and 1 tablespoon sugar until soft peaks form, about 1-2 minutes. Top chocolate filled glasses with whipped cream and garnish each cup with shaved chocolate. Serve with teaspoons.