1. Preheat oven to 350°.
2. Combine 5 1/2 ounces sugar and eggs in a large bowl, stirring with a whisk. Heat milk over medium-high heat in a small, heavy saucepan to 180° or until tiny bubbles form around edge (do not boil). Remove from heat; add cocoa and chocolate, stirring with a whisk until cocoa dissolves and chocolate melts. Gradually add hot milk mixture to sugar mixture, stirring constantly with a whisk. Stir in vanilla extract, cinnamon, and nutmeg. Add bread, tossing to coat; let mixture stand for 30 minutes, tossing occasionally.
3. Spoon bread mixture into an 8-inch square baking dish coated with cooking spray; sprinkle 1 ounce of sugar evenly over bread mixture. Bake at 350° for 40 minutes or until set. Serve warm.