In a large bowl whisk together eggs, eggnog, cinnamon, allspice, and vanilla extract. Set to the side.
In a 9x13 casserole, grease with cooking spray and add in the cubed bread in an even layer. Sprinkle the cranberries on top of the bread in an even layer throughout the pan. Pour the egg mixture over the bread and cranberries and with the back of a spatula, gently push down the bread so everything gets soaked.
Cover the pan with aluminum foil and bake for 30 minutes. After 30 minutes, remove the foil and continue baking for another 30 minutes, uncovered.
Remove from oven, sprinkle with powdered sugar (if desired) and top with pure maple syrup.