Preheat your oven to 350°F (175°C) and butter a medium baking dish.

Arrange the cubed brioche bread evenly in the prepared dish.

Whisk together the milk, heavy cream, eggs, both sugars, vanilla, cinnamon, nutmeg, and melted butter until you achieve a smooth custard mixture.

Pour the custard mixture over the brioche cubes and let soak for 20 minutes.

Bake in the preheated oven for 40 minutes or until the top is golden brown and the center is set.

Melt the granulated sugar in a saucepan over medium heat until it turns amber.

Whisk in the butter until melted, then slowly add the warm heavy cream and vanilla extract, stirring until the sauce is smooth and glossy.

Serve the warm bread pudding with the caramel sauce drizzled on top.