Big Time Sausage And Hash Brown Breakfast Casserole

2 packages sausage links
3 cups milk
9 eggs
1 teaspoon salt
1/2 teaspoon pepper
1 1/2 teaspoons ground mustard
40 ounces (2 packages) shredded hash browns
1/2 cup red bell pepper, diced
1/3 cup green onion, thinly sliced
8 ounces cheddar cheese, shredded
2 cups salsa

In a large baking dish, bake the sausage at 375 degrees for 20 minutes, or until no longer pink. Drain the fat and slice the sausage into 1/4 inch pieces.
In a large mixing bowl, combine the milk, eggs, salt, pepper and mustard. Add the sausage, hash browns, bell pepper, green onion and cheese; mix well.
Pour the egg mixture into a grease 13x9 inch baking dish. Cover and put in the refrigerator overnight.
When ready to bake, let stand for 30 minutes at room temperature. Preheat oven to 350 degrees and bake (uncovered) for 65 to 75 minutes.  Let stand for 10 minutes before serving. Serve with salsa.