Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish.

Spread the bread cubes evenly in the prepared baking dish. Sprinkle the raisins over the bread.

In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, spiced rum, granulated sugar, light brown sugar, vanilla extract, cinnamon, and salt until fully combined.

Pour the custard mixture evenly over the bread cubes, pressing down gently to ensure all the bread is soaked. Let it sit for 20-30 minutes to absorb the liquid.

Cover the dish with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 25-30 minutes, or until the top is golden brown and the center is set.

While the bread pudding bakes, make the butter rum sauce. In a small saucepan over medium heat, melt the butter. Stir in the brown sugar and cook until dissolved, about 2-3 minutes.

Slowly whisk in the heavy cream, spiced rum, and a pinch of salt. Cook for another 2-3 minutes, stirring constantly, until the sauce thickens slightly. Remove from heat.

Once the bread pudding is done, let it cool for 5-10 minutes. Drizzle the warm butter rum sauce over the top before serving. Enjoy!