01 - Preheat your oven to 350°F. Lightly grease a 9x13-inch baking dish.
02 - Place the 1-inch bread cubes into a large mixing bowl.
03 - In a separate bowl, thoroughly whisk together the whole milk, heavy cream, eggs, granulated sugar, vanilla extract, ground cinnamon, ground nutmeg, and salt until the mixture is smooth and well combined.
04 - Pour the prepared custard mixture over the bread cubes. Add the raisins and gently mix, ensuring the bread absorbs the liquid by lightly pressing the cubes. Allow the mixture to sit for 10 minutes to soak.
05 - Transfer the bread mixture into the greased 9x13-inch baking dish. Drizzle the melted unsalted butter evenly over the top.
06 - Bake for 45 to 50 minutes, or until the bread pudding is set in the center and beautifully golden brown on top.
07 - While the pudding bakes, begin preparing the bourbon sauce. Melt the unsalted butter in a small saucepan over low heat. Whisk in the powdered sugar until the mixture is smooth and lump-free.
08 - In a small separate bowl, lightly beat the remaining large egg. Slowly and continuously whisk the beaten egg into the butter-sugar mixture over low heat. Continue stirring for approximately 2 to 3 minutes until the sauce visibly thickens.
09 - Remove the saucepan from the heat. Stir in the bourbon. If making a non-alcoholic version, substitute with 2 tablespoons of vanilla extract.
10 - Serve the New Orleans Bread Pudding warm, with a generous drizzle of the bourbon sauce over each portion.