You can make a brioche french toast casserole the night before. You’d prepare the brioche custard french toast through step two then put it in the refrigerator overnight to soak up the egg mixture. In the morning, you can let it sit for 30 minutes on the kitchen counter then bake it in a 375 degree oven for 35-40 minutes. Just turn the bread over half way through the bake. You want the toast golden brown on both sides and completely cooked through.