- Preheat oven to 375°F (190°C). Grease a 9x9 casserole dish. 
- In a bowl, mix ground beef, egg, breadcrumbs, milk, onion, garlic powder, salt, and pepper until combined. 
- Press the meat mixture into the casserole dish and bake for 20 minutes. 
- Remove from oven, spread mashed potatoes evenly on top. 
- Sprinkle with shredded cheese and bacon. 
- Return to oven and bake for another 15 minutes or until cheese is bubbly. 
- Top with parsley if using. Let cool a few minutes before serving.