01 - Generously grease a 9x13 inch baking dish with butter. Arrange the bread cubes in an even layer across the bottom of the dish.
02 - In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, granulated sugar, vanilla extract, 1 1/2 teaspoons cinnamon, nutmeg, and salt. Whisk vigorously until the mixture is completely smooth and well combined.
03 - Pour the custard mixture evenly over the bread cubes. Gently press down on the bread with a spatula or your hands to help it absorb the liquid. Ensure all pieces are soaked.
04 - In a small bowl, combine the melted butter, brown sugar, 1 teaspoon cinnamon, and chopped nuts. Stir until the mixture forms a crumbly, well-blended consistency.
05 - Sprinkle the cinnamon-sugar mixture evenly over the top of the soaked bread cubes, covering the entire surface.
06 - Cover the baking dish tightly with aluminum foil. Refrigerate for at least 2 hours, or preferably overnight, to allow the bread to fully absorb the custard.
07 - Remove the dish from the refrigerator and let it sit at room temperature while the oven preheats to 350°F.
08 - Bake the covered dish for 30 minutes to allow the custard to set and the bread to steam.
09 - Remove the foil and continue baking for an additional 15 minutes, or until the top is golden brown and the custard is fully set.
10 - Let the dish rest for 10 minutes before serving. Serve warm, optionally topped with maple syrup or fresh berries.