Preheat the oven to 375F 190C. In a skillet, cook ground beef with diced onion until browned. Drain any excess fat.

Stir in garlic powder, tomato sauce, cooked rice, sour cream, salt, and pepper. Mix until well combined.

Transfer the mixture to a greased baking dish and top with shredded cheddar cheese.

Bake for 20-25 minutes, until the cheese is melted and bubbly.

Garnish with fresh parsley and serve hot.