Spray a 9x13 baking dish with non-stick cooking spray.
Place bread in the prepared dish.
Sprinkle the browned sausage over top the bread.
Sprinkle the freshly grated cheese over top the sausage.
In a medium-size bowl, beat together the eggs, milk, dry mustard, salt and pepper. Beat until all of the egg yolks are well mixed.
Pour the egg mixture over the cheese.
Cover the casserole with plastic wrap or foil and refrigerate overnight or for at least 6 hours.
Preheat the oven to 350 degrees.
Bake the casserole, covered with foil, for 30 minutes. Uncover and bake for an additional 15-20 minutes or until the middle of the casserole is puffed and set.
Cut into squares and serve warm.
The calories shown are based on the recipe being divided into 15 servings, with 1 serving being 1 piece. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.