Preheat oven to 375°F (190°C).
Grease a baking dish lightly with olive oil.
Heat skillet over medium heat, add ground beef.
Cook until browned, breaking meat into crumbles.
Drain excess fat from the skillet.
Add onions to beef, cook for 3 minutes.
Stir in garlic powder, salt, and black pepper.
Mix soup and milk in a separate bowl.
Layer half of the potatoes in the dish.
Spread half the beef mixture on top.
Pour half the soup mixture over layers.
Sprinkle half the cheese evenly across.
Repeat with remaining potatoes, beef, soup.
Cover with foil and bake for 60 minutes.
Remove foil, top with rest of cheese.
Bake uncovered for another 15 minutes.
Garnish with parsley and let rest 10 minutes.