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

Cut the brioche bread into 1-inch cubes and distribute evenly in the baking dish. Optionally, scatter raisins or pecans over the top.

Whisk together the whole milk, heavy cream, granulated sugar, brown sugar, eggs, vanilla extract, ground cinnamon, ground nutmeg, and a pinch of salt until smooth.

Pour the custard mixture over the brioche cubes, gently pressing them down to soak evenly. Let it rest for 15 minutes.

Bake for 45 to 55 minutes until the top is golden brown and a toothpick comes out clean.

To make the sauce, melt unsalted butter in a saucepan, stir in brown sugar until dissolved, then whisk in heavy cream and cook until slightly thickened. Stir in vanilla and a pinch of salt.

Remove the pudding from the oven, cool slightly, slice, and serve with warm buttery sauce drizzled on top.