Preheat oven to 350° F. Grease a 13x9-inch baking dish. Set aside.
Add the raisins and whiskey to a small bowl. Set aside.
Place the bread cubes in an even layer on a rimmed baking sheet. I use a jelly roll pan.
Lightly toast the bread cubes for 10 minutes.
Set aside.
Add the milk, eggs, sugar, vanilla, cinnamon, and nutmeg to a large bowl.
Whisk until well combined.
Add the toasted bread cubes to the prepared baking dish.
Pour the egg mixture over the bread cubes.
Add the raisins and whiskey to the bread cube mixture.
Lightly toss to coat and combine.
Let it stand 15 minutes, pushing the bread cubes into the egg mixture if needed.
Bake for 45-55 minutes, or until set and baked through. The bread pudding will be puffed and lightly browned.
To make the sauce, heat the sugar in water over low heat in a medium saucepan, stirring until sugar is dissolved and mixture is well-combined.
Bring to a boil and cook, without stirring, until caramelized, about 15 to 20 minutes.
In a separate small saucepan, warm the heavy cream over low. This will help to prevent the sugar from recrystallizing.
Add butter and warmed heavy cream to sugar mixture, and cook until well-combined, 1 to 2 minutes.
Remove from heat and let cool for 5 minutes.
Stir in the whiskey, and add additional cream if necessary.
Serve over the warm bread pudding.