Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish to prevent sticking.
Cook the turkey sausage: In a large skillet over medium heat, crumble and cook the turkey sausage until browned and cooked through, about 6-8 minutes. Drain any excess fat if needed and set aside.
Mix the wet ingredients: In a large bowl, whisk together the eggs, softened cream cheese, and milk until smooth and creamy. The cream cheese might have some lumps, but try to break them down as much as possible for a silky texture.
Add the hashbrowns and seasoning: Stir in the thawed hash browns, garlic powder, onion powder, salt, and pepper until everything is evenly combined.
Combine everything: Fold in the cooked turkey sausage and half of the shredded cheddar cheese. Mix gently to distribute the ingredients evenly.
Transfer to the baking dish: Pour the mixture into your prepared dish and spread it out evenly.
Top with remaining cheese: Sprinkle the rest of the cheddar cheese over the casserole for a golden, bubbly crust.
Bake: Place the casserole in the oven and bake for 45-50 minutes, or until the eggs are fully set and the top is golden brown.
Garnish and serve: Remove from oven and let it cool for a few minutes. Sprinkle chopped green onions on top if desired for a fresh burst of flavor.