Grease a 9x13-inch baking dish with butter or nonstick spray.

Place the sourdough bread cubes evenly in the prepared dish.

In a large mixing bowl, whisk together the eggs, milk, cream, sugar, vanilla extract, cinnamon, and salt until fully combined.

Slowly pour the custard mixture over the bread, pressing down gently so all the bread soaks up the liquid.

Cover the dish and refrigerate for at least 30 minutes, or overnight for best results.

Preheat your oven to 350°F (175°C). Uncover the dish and drizzle the melted butter over the top.

Bake for 45–50 minutes, or until golden brown and the center is set.

Let rest for 5–10 minutes before serving. Add powdered sugar, syrup, or fruit if desired.