Cut your loaf of French bread into even 1-inch cubes using a sharp serrated knife. Place the bread pieces into a greased baking dish and spread them out into an even layer.

In a large mixing bowl, whisk together the eggs, milk, heavy cream, and granulated sugar. Add the vanilla extract and half of the cinnamon to create a very fragrant and creamy liquid.

Slowly pour the egg and milk mixture over the bread cubes in the baking dish. Press down gently with a spoon to make sure every piece of bread absorbs the sweet custard.

Cover the dish with plastic wrap and let it sit in the fridge for at least thirty minutes. Chilling allows the bread to soak up all the flavors without becoming too thin or runny.

In a small bowl, combine the brown sugar, flour, salt, and the remaining ground cinnamon. Stir them together until the dry ingredients are well-mixed and ready for the cold butter.

Add the cold butter cubes to the sugar mixture using a fork or your clean fingers. Work the butter in until the topping looks like coarse crumbs or small pea-sized pieces.

Remove the dish from the fridge and sprinkle the cinnamon crumble evenly over the soaked bread. This layer provides the amazing crunch that makes this French Toast Casserole Recipe so special.

Set your oven to 350°F and let it reach the full temperature before you start baking. A hot oven is the secret to getting a golden crust and a soft middle.

Place the dish in the center of the oven and bake for forty-five to fifty minutes. You want the top to be deep golden brown and the custard to be set.

Let the casserole rest for five minutes before slicing it into large, warm squares. Serve with maple syrup or fresh berries while it is still hot and smelling wonderful.