Preheat your oven to 350°F (175°C).
Grease a 9x13 inch baking dish with butter or cooking spray.
Cut the bread into cubes and place them in the greased dish.
In a large bowl, whisk together the eggs, milk, sugar, vanilla, cinnamon, and salt.
Pour the egg mixture evenly over the bread cubes.
Gently toss the bread to ensure all pieces are soaked.
Cover the dish with plastic wrap and refrigerate for at least an hour (or overnight).
Remove from refrigerator and let it sit for 10 minutes at room temperature.
Bake in the preheated oven for 45 minutes, or until golden brown.
Serve warm, dusted with powdered sugar and topped with maple syrup and berries if desired.