Preheat the oven to 350°F (175°C).

In a large skillet over medium heat, cook the breakfast sausage until browned and fully cooked, breaking it apart with a spatula.

In a mixing bowl, whisk together the eggs, milk, salt, pepper, garlic powder, and onion powder until well combined.

In a greased 9x13 inch baking dish, spread the thawed hash browns evenly across the bottom.

Layer the cooked sausage over the hash browns.

Pour the egg mixture over the sausage and hash browns, ensuring everything is evenly coated.

Sprinkle the shredded cheddar cheese on top, followed by the chopped green onions and diced bell pepper.

Bake in the preheated oven for 45-50 minutes, or until the eggs are set and the top is golden brown.

Let the casserole cool for a few minutes before slicing and serving.