Preheat your oven to 375°F (190°C) and grease a 9x13 inch baking dish.
In a large mixing bowl, whisk together the eggs, milk, sugar, vanilla, cinnamon, nutmeg, and maple syrup until smooth.
Place the cubed brioche bread in the greased baking dish, and pour the egg mixture evenly over the top. Gently press the bread down with a spatula to help it soak up the liquid.
If using, sprinkle the chopped pecans over the bread mixture for added crunch and flavor.
Cover the dish with aluminum foil and let it rest in the refrigerator for at least 30 minutes or overnight for best results.
Once ready to bake, remove the foil and bake in the preheated oven for 30-35 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
Let it cool for about 10 minutes, then dust with powdered sugar if desired. Serve warm with additional maple syrup drizzled on top.
Notes
For best results, let the casserole rest overnight in the refrigerator.
Keyword breakfast, brioche, casserole, French toast