Creating Old Fashioned Bread Pudding with Rum Sauce is straightforward if you follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish with butter.
2. Prepare Bread: In a large bowl, combine the cubed bread and melted butter. Stir until the bread is well-coated.
3. Mix Wet Ingredients: In another bowl, whisk together the milk, eggs, sugar, vanilla extract, cinnamon, nutmeg, and salt until well combined.
4. Combine Mixtures: Pour the wet mixture over the buttered bread. Gently toss to ensure all the bread is soaked. If using raisins, fold them in at this stage.
5. Let It Sit: Allow the mixture to sit for about 15 minutes to let the bread absorb the liquid.
6. Transfer to Baking Dish: Pour the soaked bread mixture into the prepared baking dish, spreading it evenly.
7. Bake: Place the dish in the preheated oven and bake for 45 minutes, or until the top is golden brown and a knife inserted in the center comes out clean.
8. Cool: Once baked, remove the dish from the oven and let it cool for about 15 minutes before serving.
9. Prepare the Rum Sauce: In a saucepan over medium heat, combine brown sugar, heavy cream, butter, rum, and vanilla extract. Stir until the mixture is smooth and begins to thicken. Remove from heat.
10. Serve: Drizzle the warm rum sauce over individual servings of bread pudding.