Soak the raisins for 30 minutes in warm water, then drain well.
Fill a 9-inch square baking pan with the bread cubes and sprinkle the raisins on top. (Use enough bread to come to the top of the pan. The whole loaf may not be required.)
Whisk the remaining ingredients together to make a batter, pour over bread, and stir lightly. Allow the bread to soak 1/2 hour. (The pan will be very full. If you have too much batter, discard the excess. If there's not enough, add a little more milk to the pan.)
Bake at 325° F for about 40 minutes, until the pudding is golden brown and puffed up around the edges. The center should be set but still a little soft. You can make this ahead of time, and heat it in the microwave oven later.
Yields 4 servings.
Makes: 4