Coat an 11-by-7-inch baking dish with 1 tablespoon of the butter. Place the bread cubes in a single layer in the dish.
In a large bowl, combine the milk, sugar, eggs, vanilla, nutmeg or mace, and salt. Pour the milk mixture over the bread and dot with the remaining butter. Cover and refrigerate for 1 hour.
Preheat oven to 350° F. Bake the pudding for 40 to 45 minutes or until golden brown. Serve warm.