01 - Preheat oven to 350°F. Generously butter a 9x13-inch baking dish to prevent sticking.
02 - Spread bread cubes evenly in prepared dish. If using raisins, sprinkle them over the bread layer.
03 - Whisk together milk, cream, eggs, sugar, vanilla extract, cinnamon, nutmeg, and salt in a large bowl until fully combined.
04 - Pour custard evenly over bread, pressing down gently to ensure absorption. Let stand for 10 minutes.
05 - Drizzle melted butter over the soaked bread cubes.
06 - Bake for 40-45 minutes until golden brown and set in center.
07 - Combine milk, cream, sugar, and butter in saucepan. Heat over medium, stirring until sugar dissolves and mixture is hot but not boiling.
08 - Mix cornstarch and cold water to form slurry. Stir into sauce and cook, stirring constantly, for 2-3 minutes until thickened.
09 - Remove from heat. Stir in vanilla extract and pinch of salt.
10 - Serve warm bread pudding with generous spoonfuls of warm vanilla sauce.