• Preheat oven to 350℉/175℃.
• In a small bowl, pour the whiskey over the raisins and stir to combine. Let them soak for at least an hour or more. Set aside.
• Cut the bread into 1-inch cubes. Pour the milk into a large bowl and add the bread cubes. Use your hands to press all the bread into the milk until all pieces are covered.
• Add eggs, sugar, vanilla, allspice, cinnamon, and nutmeg to a separate medium bowl. 
• Beat the egg mixture until thoroughly combined and pour it over the bread mixture. Then add the whiskey-soaked raisins. Stir very gently with a wooden spoon, making sure the bread pieces don't break apart.
• Take softened butter using a paper towel or cloth and spread it around a 9x13 baking pan, making sure to coat the sides and bottom. Alternatively, use a spray.
• Pour the bread pudding mixture into the pan and bake for 30-40 minutes. When done, the pudding should be slightly brown, and the edges should start to pull away from the sides. Let it cool for 10 minutes before serving.

Rum Sauce

• Combine butter, heavy cream, brown sugar, granulated sugar, salt, and rum into a small saucepan over medium heat and simmer until sauce thickens; it takes about 10 minutes.
• The sauce will continue to thicken as it cools. If it gets too hard, add a tablespoon of heavy cream or milk to thin it out.
• Pour immediately over bread pudding and serve.