Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch glass baking dish with cooking spray or olive oil.
Arrange the meatballs in a single layer in the prepared baking dish. They can be slightly touching but not piled up.
Pour the marinara sauce evenly over the meatballs. Sprinkle the dried oregano, basil, garlic powder, salt, and pepper over the sauce.
Sprinkle the shredded mozzarella and grated Parmesan evenly over the top of the casserole.
Place the dish in the preheated oven and bake uncovered for 25-30 minutes, until the sauce is bubbly and the cheese is melted and lightly browned.
Remove from the oven and let rest for 5 minutes. Sprinkle with fresh parsley before serving directly from the baking dish.