To make an overnight egg casserole, cook 1 pound of ground pork sausage over medium heat until browned evenly. Drain the sausage and set it aside. Mix together 4 beaten eggs, 2 cups of milk, 1 teaspoon of mustard powder and 1/2 teaspoon of salt.
Toast 6 slices of white bread and cut them into cubes. Add the bread, cooked sausage and 8 ounces of cheddar cheese to the egg mixture and stir until bread is evenly coated.
Pour the mixture into a greased 9x13-inch baking dish. Cover the dish and chill the casserole in the refrigerator overnight.
Preheat the oven to 350 degrees Fahrenheit and bake the casserole, covered, for 45 to 60 minutes. Uncover the casserole, reduce the oven temperature to 325 degrees Fahrenheit, and continue to bake for 30 minutes.
To make an overnight French toast egg casserole, add 1/3 cup of melted butter or margarine to the bottom of a 9x13-inch baking dish. Arrange six slices of bread in the bottom of the dish. Sprinkle 1/2 cup of brown sugar and 1 teaspoon of cinnamon over the bread. Add a second layer of 6 bread slices.
Whisk six eggs with 1 1/2 cups of milk and pour the mixture over the bread. Sprinkle the top with 1/2 cup of brown sugar and 1 teaspoon of cinnamon. Cover the casserole and refrigerate overnight.
Bake the covered casserole at 350 degrees Fahrenheit for 30 minutes. Uncover the dish and bake for an additional 30 minutes.