Preheat the oven to 350°F (175°C).
In a large mixing bowl, whisk together the eggs, milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, and salt until well combined.
Place the cubed French bread in the baking dish. Pour the egg mixture evenly over the bread cubes. Gently press down to ensure all the bread is soaked.
If preparing ahead of time, cover with aluminum foil and refrigerate for at least 2 hours or overnight.
Uncover the casserole (if refrigerated) and bake in the preheated oven for 45 minutes, or until the top is golden brown and the center is set.
Remove from the oven and let it cool for a few minutes. Serve warm with maple syrup drizzled on top and a dusting of powdered sugar if desired.
Feel free to add fruit, such as berries or sliced bananas, to the mixture before baking for added flavor and texture.
This casserole can also be frozen before baking; just thaw in the refrigerator overnight before cooking. Adjust cooking time if needed.