Grease a 9x13 inch baking dish with butter or non-stick spray.
Place the cubed bread evenly in the baking dish.
In a large mixing bowl, whisk together the eggs, milk, heavy cream, sugar, vanilla extract, cinnamon, and salt until well combined.
Pour the egg mixture over the bread cubes, making sure all pieces are soaked. Gently press down to ensure all bread is covered.
Cover the baking dish with aluminum foil and refrigerate overnight, or for at least 4 hours.
Preheat the oven to 350°F (175°C).
Remove the casserole from the refrigerator and let it sit at room temperature for about 15 minutes before baking.
Bake, covered with foil, for 30 minutes. Then remove the foil and bake for an additional 15 minutes, or until the top is golden brown and the casserole is set.
Let it cool slightly before serving.
Drizzle with maple syrup, and dust with powdered sugar and fresh berries if desired.