Place the raisins in a small bowl.

In a small saucepan, heat the rum extract over medium heat. Pour the rum over the raisins, cover, and let soak at least 30 minutes and up to 2 hours. Drain.

Scrape the vanilla bean seeds into a small ramekin and reserve.

Combine water, rice and vanilla bean pod in a heavy, medium saucepan. Bring to a boil, then reduce heat to medium-low and simmer, covered, until the rice is tender and the liquid is absorbed, about 20 minutes.

Uncover rice, discard the vanilla bean, and let cool.

Preheat oven to 350 degrees F.

Butter 1 large (6 to 8-cup) souffle dish with the tablespoon of butter, and place inside a roasting pan.

In a large bowl, whisk together the milk, brown sugar, eggs, egg yolk, salt and reserved vanilla seeds. Stir in the raisins and cooked rice. Pour into the buttered dish. Place the dish in a large roasting pan. Add enough hot water to the roasting pan to come halfway up the sides of the dish. Bake until the pudding is set in center and brown around edges, about 1 hour and 5 minutes. Remove the dish from the water and cool at least 15 minutes before serving.

Serve warm with whipped cream, if desired.