Preheat oven to 400° F. Finely chop 1/2 an onion, process bread into crumbs in a processor, and combine all ingredients for the meatballs including seasonings.
Using washed and clean hands, roll the meatballs into 2-inch diameters and place on foil on rimmed baking sheet (otherwise fat will run off). Continue making meatballs until ingredients are all used up. You should end up with about 16 large meatballs.
Place the meatballs on the baking sheet or foil, spacing them 1 inch apart. Bake until they are cooked through, about 25 minutes. .
While the meatballs are cooking, bring a large pot of water to a boil with salt for the spaghetti and warm the spaghetti sauce in a saucepan over medium-low heat. Add extra seasoning like Italian, parsley, oregano, and basil.
Cook the spaghetti according to package directions; drain and plate accordingly.
When meatballs are almost cooked through, add a few sprinkles of mozzarella cheese and broil until browned. Remove from oven and let cool for a few minutes.
Sprinkle some parsley flakes on top of the meatballs and serve with readied spaghetti and sauce. Garlic bread would also be a nice addition to this Italian meal!