
Preheat the oven to 375F. Lightly grease a 13x9-inch baking dish with butter.
In a large bowl, whisk together the eggs, milk, brown sugar, vanilla, cinnamon, and salt. Stir in the bread until fully coated. Spoon into the prepared baking dish.
In a small bowl, whisk together the brown sugar, cinnamon, and salt. Sprinkle the mixture and the butter evenly over the bread mixture.
Bake for about 30 minutes or until the filling is set and the top is golden brown. Cool for a few minutes before serving. Serve with powdered sugar and maple syrup, if desired.