Preheat oven to 325. In large skillet, cook sausage over medium high heat, stirring frequently, til thoroughly cooked and no longer pink. (I use turkey sausage).
In large mixing bowl, mix eggs, milk, mustard and salt; stir well. Distribute half the bread cubes evenly in buttered 9 x 13 inch baking dish. Sprinkle with half the pepper; half the cheese, half the sausage and half of each optional ingredients. Repeat layering, using remaining bread cubes, pepper, cheese, sausage and optional ingredients. Pour egg mixture evenly over casserole.
Bake uncovered, for 55 to 60 minutes or til eggs are set. Tent with foil if top begins to brown too quickly. Makes 6 servings. This can be assembled and refrigerated for up to 12 hours before baking.