Preheat oven to 350 degrees F. Lightly coat 12 ovenproof espresso cups (the equivalent of six 4 ounce ramekins) with nonstick cooking spray (or line 2-1/2-inch muffin cups with a double thickness of foil bake cups); set aside. Place bread cubes and 1/2 cup Ghirardelli(R) 60% Cacao Bittersweet Chocolate Baking Chips into prepared cups. Tuck pieces of Ghirardelli Milk & Caramel SQUARES(TM) Chocolate into each cup.
In a medium bowl, whisk together eggs, the 1-1/2 cups half-and-half, the 1/4 cup sugar, the vanilla, and cinnamon. Slowly pour milk mixture over bread and chocolate squares, allowing the bread to soak up the egg mixture.
Place filled cups in a shallow baking pan. (If using muffin pans, they can be placed directly in the oven.) Bake, uncovered, about 25 minutes or until tops are puffed and a knife inserted near centers comes out clean. Cool in cups for 5 minutes.
Meanwhile, for sauce, in a small heavy saucepan, heat and stir the 1/2 cup Ghirardelli 60% Cacao Bittersweet Chocolate Baking Chips and the butter over low heat. Add the 1/3 cup sugar; gradually stir in the 1/4 cup half-and-half; stir to dissolve the sugar. Bring to a boil; reduce heat. Boil gently over low heat for 6 minutes, stirring frequently. Remove from heat. If desired, stir in liqueur. Cool slightly. Serve sauce over puddings.
Any leftover puddings and sauce may be cooled completely, covered, and stored separately in the refrigerator for up to 3 days.