Using a vegetable peeler, remove zest (orange part only) from the oranges (save oranges for another use). In a medium saucepan, combine half-and-half and orange zest. Cook and stir over medium heat until mixture just comes to boiling. Remove from heat. Cover and let stand for 30 minutes.
Strain milk into a medium bowl; discard orange zest. Return milk to saucepan. Stir in Ghirardelli(R) Double Chocolate Hot Cocoa mix. Heat through but do not boil. Remove saucepan from heat. If desired, stir in liqueur. Serve in demitasse cups or shot glasses. Top with marshmallows and, if desired, Sugared Orange Zest.
Sugared Orange Zest: Using a vegetable peeler, remove zest (orange part only) from 1 orange (save orange for another use). Cut the zest into thin strips. Toss the strips in a small amount of sugar (2 to 3 tablespoons) to coat.