Preheat the Oven: Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.

Prepare the Bread: Cut the loaf of French bread into 1-inch cubes and spread them evenly in the prepared baking dish.

Make the Custard Mixture: In a large bowl, whisk together the whole milk, heavy cream, eggs, sugar, and vanilla extract until fully combined. For a citrusy twist, stir in the orange zest (optional).

Soak the Bread: Pour the custard mixture over the bread cubes, making sure all the bread is soaked evenly. Allow the mixture to rest for approximately 10 minutes so the bread can soak up the custard.

Bake: Transfer the baking dish to the preheated oven and cook for 45 to 50 minutes, or until the top is a beautiful golden brown and a knife inserted in the middle comes out clean.

Cool: Take the bread pudding out of the oven and let it cool for a few moments before slicing and serving.

Heat the Cream: In a small saucepan over medium heat, combine the heavy cream and sugar, stirring until the sugar dissolves.

Thicken the Sauce: In another bowl, mix the cornstarch with 2 tablespoons of water until fully combined. Gradually whisk this mixture into the hot cream, stirring constantly until the sauce thickens, about 3-4 minutes.

Add Vanilla and Butter: Remove the saucepan from heat and stir in the vanilla extract and butter, mixing until the butter melts and the sauce is smooth.

Serve: Pour the warm vanilla sauce generously over each serving of bread pudding and savor the delightful flavors!