Prepare the Bread Pudding:

1. Preheat your oven to 350°F (175°C) and lightly grease a 9×13-inch baking dish.
2. Arrange the cubed bread in the prepared dish. Sprinkle raisins over the bread if desired.
3. In a large bowl, whisk together the milk, eggs, sugar, vanilla, cinnamon, and nutmeg until smooth.
4. Pour the custard mixture evenly over the bread, ensuring every piece is soaked. Let it sit for 10 minutes to absorb.
5. Bake in the preheated oven for 45-50 minutes or until the top is golden and the center is set.

Make the Vanilla Sauce:

1. In a small saucepan, whisk together the sugar and cornstarch. Gradually add the heavy cream, whisking until smooth.
2. Add the butter and cook over medium heat, stirring constantly, until the mixture thickens and boils.
3. Boil for 1 minute, then remove from heat and stir in the vanilla extract.

Serve and Enjoy:

1. Drizzle the warm vanilla sauce generously over the bread pudding just before serving.
2. Enjoy the comforting combination of custard-soaked bread and rich, creamy sauce with every bite.