Browned, drained and crumbled.
Grease large, flat baking dish.
Completely cover bottom of dish with bread slices, allowing them to rise along sides slightly for crust. Spread cooked sausage to cover. Spread cheese to cover.
Mix eggs, milk and mustard; pour over casserole.
Refrigerate overnight (it doesn't really work if you don't)
Next morning, preheat oven to 375.
Mix soup and milk and cover casserole.
Bake for l hour 15 minutes or until completely set.