Preheat the oven to 400°F.
In a large bowl, combine ground meat, tablespoons of grated Parmigiano, egg, bread cubes, garlic powder, parsley, and oregano to get a homogeneous mixture.
Form meatballs in the desired size.
In a large skillet, heat 3 tablespoons of extra virgin olive oil and finely chopped onion. Cook and stir for 5 minutes over medium heat until golden brown.
Add tomato sauce and cook for an additional 5 to 8 minutes.
Now add meatballs, reduce the heat, and cook covered for 10 minutes. Stir gently to turn over the meatballs and continue cooking uncovered.
Season with salt and cook for another 10 to 15 minutes until the meatballs are cooked.
Cook spaghetti as indicated on the package instructions. Drain them 2 minutes before the time indicated on the package.
Transfer the meatballs onto a plate.
Combine pasta with sauce.
Transfer the pasta into a round baking dish.
Top with meatballs and grated Parmigiano.
Bake for a couple of minutes until the cheese has melted.
Garnish with basil leaves.
Serve and enjoy.