In a large bowl, combine the thawed hash browns, cooked sausage, chopped onion, chopped green bell pepper, salt, and pepper. Mix well.
In a separate bowl, whisk together the eggs and milk until well combined.
Pour the egg mixture over the hash brown mixture and stir gently to combine.
Pour the entire mixture into a greased 9×13 inch baking dish.
Sprinkle the shredded cheddar cheese evenly over the top.
Bake for 45-55 minutes, or until the casserole is set and the cheese is melted and lightly golden.
Let the casserole stand for 5-10 minutes before serving.
Notes
For a make-ahead option, assemble the casserole the night before, cover, and refrigerate. Bake as directed, adding a few extra minutes to the cooking time if needed.
To reheat leftovers, cover the dish with foil and warm in a 300°F (150°C) oven until heated through.
You can substitute other cooked meats like bacon or ham for the sausage.
Add other vegetables like mushrooms or jalapeños for extra flavor.