Preheat oven to 350°F. Coat an 8-inch square baking dish with nonstick cooking spray. Spread bread in the dish in an even layer.
Whisk eggs in a medium bowl. Add evaporated skim milk, sugar, cocoa, vanilla and cinnamon; whisk the mixture until the sugar and cocoa dissolve. Pour the cocoa mixture over the bread. Mix in any unsoaked bread pieces. Sprinkle chocolate over the top and let stand for 10 minutes.
Bake until puffed and set in the center, 35 to 40 minutes. Serve warm, with a scoop of frozen yogurt on top. The pudding is also good cold.