Butter a 2-quart baking dish. Cut into 1-inch cubes. Spread the bread evenly in the prepared baking dish then scatter the raisins over the top. Whisk together eggs, sugar, vanilla, cinnamon, nutmeg, salt, and 3 cups milk. Pour the mixture over the bread and let stand for 30 minutes. Periodically pressing the bread down with a spatula to help it absorb the liquid.
Preheat the oven to 350 degrees F.
Bake the pudding in a water bath until puffed and firm in the center, about an hour and 20 minutes. Serve warm or cold with cream.