In a large bowl, mix together the dry ingredients (salt, pepper, Parmigiano, parsley, and garlic), and then add the beaten eggs. Dip the bread in milk or water, squeeze out some of the liquid and then mix it into the egg mixture Once the ingredients are thoroughly combined, add the meat and mix thoroughly by hand. If the mixture seems dry, add a tablespoon or two of water.
Take a small amount of the meat mixture and shape into a small ball (about the size of a large marble), until you have formed all the balls. In a large skillet, heat about 1/4 cup of olive oil. When the oil is hot, place the meatballs in the skillet, with enough room to allow you to easily flip them over. Cook the meatballs on a low heat until brown on all sides (but being careful not to burn them). Remove the meatballs from the skillet place on a paper towel to drain.
Prepare the Sauce:
Chop the onion and fry it in the olive oil and skillet used to fry the meatballs. When the onion is golden, add the tomatoes, salt, and pepper. Cook on low heat, uncovered for 20-30 minutes until reduced.
Assemble the Pasta:
Preheat oven to 350 degrees F.
Bring a large pot of salted water to a boil. Cook the pasta for half of the package recommendation, until very al dente. Drain the pasta and place into a baking dish. Mix in 2/3 of the cheese, the meatballs, and most of the sauce. Sprinkle with Parmigiano and remaining mozzarella.