Grease a baking dish with butter.
Arrange the slices of bread in the dish, slightly overlapping.
In a bowl, whisk together the eggs, milk, cream, maple syrup, vanilla, cinnamon, and salt.
Pour the egg mixture evenly over the bread slices.
Cover the dish with plastic wrap and refrigerate overnight.
Preheat the oven to 350°F (175°C) the next morning.
Bake the French toast for 30-35 minutes until golden brown and set.
Let it cool for a few minutes before serving.
Dust with powdered sugar and serve with your choice of toppings.
Enjoy your delicious overnight French toast!