Preheat oven to 350°F.
Slice the bread into 2-inch cubes and spread them out on a baking sheet. Bake for 10 minutes, until the bread feels dry but is not browned.
1 (1-pound) loaf brioche bread
Grease a 9x13-inch baking pan with butter. Add the bread to the dish and spread it out into an even layer.
In a large bowl, whisk the milk, melted butter, vanilla extract, sugar, cinnamon, salt, and eggs together.
4 cups milk, ¼ cup unsalted butter, 1 tablespoon pure vanilla extract, ⅔ cup granulated sugar, 1 teaspoon ground cinnamon, ¼ teaspoon kosher salt, 4 large eggs
Pour the liquid mixture over the bread. Use a spatula to wiggle the bread around and let it soak into all the cracks between the bread cubes.
Let the mixture sit at room temperature for 30 minutes to absorb the liquid. You can also cover it and refrigerate it overnight.
Bake for 45 minutes, until set and golden brown on the top. Let cool for 5 minutes before serving with powdered sugar, maple syrup, and/or fresh berries, if desired.
Powdered sugar, Maple syrup, Fresh berries