Prep the pan and oven: Heat the oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter. This size gives the pudding a nice balance of creamy center and toasty top.

Cube the bread: Cut the bread into 1-inch cubes. If it’s very fresh, spread the cubes on a sheet pan and toast at 300°F (150°C) for 10 minutes to dry them slightly.

Make the custard: In a large bowl, whisk eggnog, eggs, sugar, melted butter, vanilla, nutmeg, cinnamon, and salt until smooth. Taste a small spoonful of the custard (before adding bread) to gauge sweetness and adjust sugar if needed.

Combine: Add the bread cubes and any add-ins to the bowl. Toss gently to coat every piece. Let the mixture sit for 10–15 minutes, stirring once or twice, so the bread fully absorbs the custard.

Transfer to the dish: Pour everything into the prepared baking dish. Spread it into an even layer and sprinkle a pinch of nutmeg over the top for extra aroma.

Bake: Bake for 35–45 minutes, until the edges are set and the center is puffed but still slightly soft. A knife inserted in the center should come out mostly clean, with a bit of moisture but no raw custard.

Rest and serve: Let the pudding rest for 10 minutes to set. Serve warm with caramel sauce, a dusting of powdered sugar, or a drizzle of maple syrup. A dollop of whipped cream or vanilla ice cream is never a bad idea.