Preheat the oven to 350°F (175°C).
Prepare the bread: Slice the French bread into 1-inch thick slices and arrange them in a greased 9x13-inch baking dish.
Make the custard: In a mixing bowl, whisk together the eggs, milk, half-and-half, brown sugar, vanilla, cinnamon, and salt.
Pour the custard: Pour the custard mixture over the bread slices, making sure they are all soaked. Press the bread down gently to ensure it absorbs the mixture.
Refrigerate: Cover the dish and refrigerate for at least 1 hour or overnight for best results.
Bake: Bake the casserole in the preheated oven for about 45 minutes or until the top is golden and crispy.
Garnish: After baking, let the casserole cool for about 10 minutes before serving. Optionally, dust with powdered sugar and top with fresh berries, pecans, and maple syrup.