Preheat the oven to 350ºF. If using raisins, soak them in hot water. Butter a 1½-quart casserole dish (I used a 8″ x 10″ rectangular pan). Toast the bread in a toaster or on a griddle and spread with butter. Cut up or break the bread into approximately 2-inch chunks and place randomly in casserole. Sprinkle with brown sugar and cinnamon. Drain the raisins and sprinkle them over the bread. In a blender, combine the eggs, granulated sugar, vanilla, salt, and milk. Blend for about 1 minute. Pour over the bread. Place the casserole in a larger pan of very hot water, about 1 inch deep. Bake for about one hour, or until a knife comes up clean. Remove the casserole from water. Serve warm or cold.