- Grease a large baking dish with butter.
- Butter the bread on both sides and cut into triangular quarters, keeping the crusts on.
- Layer the sliced bread in the dish, overlapping the slices and sprinkling with raisins as you go. Continue until everything is used up and the dish is full, finishing with a sprinkling of raisins.
- Add the cream, milk and eggs to a large bowl. Split the vanilla pod in half lengthways and scrape in the seeds. Whisk together to make a smooth custard.
- Pour the custard over the dish to completely cover the bread. Allow to soak in completely for an hour in the fridge - you can lightly press the bread down with your hands to help it soak in if needed.
- When ready to cook, preheat the oven to 180°C/Fan 160°C/Gas 4.
- Sprinkle the top of the pudding with the demerara sugar then stand the baking dish in a large, deep roasting tin or baking tray. Pour hot water from the kettle into the outer tray so that it comes about halfway up the sides of the baking dish to create a bain-marie.
- Bake for 35-40 minutes or until the pudding is golden on top and the custard just set. Serve hot or at room temperature with custard or ice cream