Preheat your oven to 350°F (180°C) and grease a 13x9 inch baking dish with butter or cooking spray.

In a large mixing bowl, combine sugar, vanilla extract, cinnamon, and nutmeg. Whisk together, then add eggs one at a time while whisking.

Gradually pour in the eggnog, stirring until smooth.

Scatter bread pieces in the greased baking dish and pour the custard mixture over the bread, tossing gently to coat.

Press bread down lightly and cover the dish with plastic wrap or foil. Let it sit at room temperature for 30 minutes.

Uncover and bake for 45-55 minutes until golden brown and edges are set.

Allow to cool for 20-30 minutes before serving, dust with powdered sugar and garnish as desired.