Preheat your oven to 400°F (200°C).

In a large skillet over medium heat, add ground beef and chopped onion. Cook until the beef is browned, about 8–10 minutes. Drain excess fat, and season with salt and pepper.

In a mixing bowl, combine the cooked beef mixture with shredded cheddar cheese, milk, eggs, flour, baking powder, and garlic powder. Stir until well combined.

Pour the beef mixture into a greased pie dish, spreading it out evenly.

Sprinkle the remaining cheddar cheese over the top of the beef mixture in the dish.

Place the pie in the oven and bake for 25–30 minutes until the top is golden brown and the pie is set.

Remove from the oven and let it cool for a few minutes before slicing into wedges.