Place the milk in a medium, heavy saucepan; bring to a boil. Combine sugar, cornstarch, coffee, and salt in a large bowl, stirring well. Combine half-and-half and egg yolks. Stir egg yolk mixture into sugar mixture. Gradually add half of hot milk mixture to sugar mixture, stirring constantly with a whisk. Return hot milk mixture to pan; bring to a boil. Reduce heat, and simmer 1 minute or until thick, stirring constantly. Remove from heat. Stir in butter and liqueur.
Spoon pudding into a bowl. Place bowl in a large ice-filled bowl for 15 minutes or until pudding is cool, stirring occasionally.
Cover the surface of the pudding with plastic wrap; chill. Sprinkle each of the servings with 1 teaspoon dark chocolate shavings.