Pour the melted butter into the bottom of a 9x13 baking dish. Sprinkle the brown sugar over the bottom of the dish.
4 Tablespoons melted butter, ½ cup brown sugar
Cut the slices of brioche in half and then arrange the bread slices in the casserole pan. It is okay if they overlap a little bit. I like to try to line then up, laying one slightly on top of the next.
1 (16 ounce) loaf of brioche bread, sliced
In a medium sized bowl, whisk together the eggs, milk, maple syrup, vanilla extract, cinnamon and salt.
9 eggs, 1 cup whole milk, ½ cup maple syrup, 1 Tablespoon vanilla extract, 1 ½ teaspoons ground cinnamon, ¼ teaspoon salt
Pour the egg mix over the bread in the casserole dish. Try to pour the egg mix over every piece of bread.
Let the brioche French toast casserole sit for about 30 minutes. This will let it really soak up the eggs, milk and delicious flavor.
Preheat the oven to 350 degrees F.
Cover the casserole loosely with foil then bake the casserole in the hot oven for 20 minutes. Remove the foil from the pan and bake for another 10 minutes.
Remove the casserole from the oven, slice and serve while warm.