Preheat your oven to 350°F (175°C). This step begins the magic!

Spread the bread cubes evenly on a rimmed baking sheet. Bake until they're nearly dried, around 10 minutes, then let them cool.

Lower the oven temperature to 300°F (150°C).

In a large bowl, whisk together the brown sugar, granulated sugar, cinnamon, and nutmeg until well mixed.

Next, add the eggs and egg yolks, whisking until fully integrated.

Blend in the whole milk, heavy cream, and vanilla extract until smooth.

Pour this mixture over the bread cubes, tossing them gently until each piece is coated. Let it rest for 15-30 minutes; this allows the bread to soak up that creamy goodness.

Meanwhile, spread the melted butter into a casserole dish.

Pour the soaked bread mixture into the dish, spreading it evenly.

Bake in the preheated oven until the center is set, about 50-65 minutes. It should have a golden-brown top and a slightly jiggly center.

Let it cool for about 10 minutes before cutting into squares. Serve warm, perhaps with a drizzle of sauce or a dollop of whipped cream if you're feeling indulgent!