1. Butter a 9-by-13-inch baking dish.
2. In a large bowl, whisk together the milk (2 cups), eggs (4 large), packed light brown sugar (1/4 cup), ground cinnamon (1 teaspoon), vanilla extract (1 teaspoon), and fine salt (1/2 teaspoon).
3. Dip each slice of Trader Joe’s Pumpkin Brioche Twist (1 loaf) into the milk mixture, then arrange in the prepared baking dish in slightly overlapping layers. Pour any remaining milk mixture evenly over the top. Gently press the bread into the custard, cover with foil, and refrigerate overnight (or at least 8 hours ).
4. When ready to bake, preheat the oven to 350°F (175°C). Uncover the baking dish and gently flip each piece of bread so the side that is more saturated with custard is facing up. Rearrange the slices decoratively as needed so the crust edges are exposed. Dot the top with the cubed unsalted butter (3 tablespoons) and cover the dish tightly with foil.
5. Bake for 15 minutes , then remove the foil and bake until lightly browned, slightly puffy in the center, and cooked through, about 15-20 minutes more. Tent loosely with foil if the top browns too quickly.
6. Let cool slightly before serving with maple syrup and toasted chopped walnuts, if desired.

Tips & Notes

• Bread Selection: We use Trader Joe’s Pumpkin Brioche Twist instead of plain brioche. Since the loaf is already swirled with pumpkin purée and warming spices, we add ground cinnamon to the custard rather than a separate pumpkin spice blend.
• Flipping the Bread: Flipping each slice before baking ensures the custard is evenly distributed throughout the casserole and allows the exposed top crusts to bake up beautifully crisp and golden.
• Make-Ahead: Assemble the casserole the evening before for an effortless holiday or weekend morning bake.