Preheat your oven to 375°F (190°C).
In a large skillet, cook the ground beef and chopped onion over medium heat until the beef is browned. Drain the excess grease.
In a large bowl, mix together the sour cream, cream of mushroom soup, garlic powder, onion powder, salt, and pepper.
Stir in the thawed hashbrowns, cooked beef mixture, and 1 1/2 cups of the shredded cheese.
Spread everything evenly in a greased 9x13 inch baking dish. Top with the remaining 1/2 cup of cheese.
Bake uncovered for 35–40 minutes, or until the top is golden and the edges are bubbly.
Garnish with chopped parsley if you’re feeling a little fancy, and serve hot.