- 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 as it cooks. Drain any excess grease. 
- In a large mixing bowl, combine the softened cream cheese, eggs, milk, garlic powder, onion powder, salt, and pepper. Whisk until smooth and well combined. 
- In a greased 9x13-inch baking dish, spread the frozen hashbrowns evenly across the bottom. 
- Layer the cooked sausage over the hashbrowns, followed by the egg and cream cheese mixture. 
- Sprinkle the shredded cheddar cheese on top. 
- Bake in the preheated oven for 45-50 minutes, or until the casserole is set and the top is golden brown. 
- Remove from the oven and let it cool for 5-10 minutes before serving. Garnish with chopped green onions if desired.