In a large skillet, heat a splash of oil over medium heat. Add your breakfast sausage, breaking it apart and cook for 5-7 minutes until browned.

In a large mixing bowl, whisk together eggs, milk, sour cream, salt and pepper until smooth.

In a greased 9x13-inch baking dish, layer half of the hash browns, followed by half of the sausage and half of the cheddar cheese. Repeat with remaining ingredients.

Pour the egg mixture over the layered ingredients, ensuring even distribution.

Cover tightly with aluminum foil and refrigerate for at least 8 hours or overnight.

Preheat oven to 350°F (175°C). Remove foil and bake for 45 minutes covered, then uncover and bake an additional 20-25 minutes.

Let the casserole rest for 5 minutes, then sprinkle with chopped green onions and serve warm.