Soak the bread crumbs in the milk in a large bowl for 5 minutes. Add the ground beef, parsley, onion powder, garlic powder, basil, oregano, salt, pepper, Parmigiano-Reggiano cheese, and egg. Mix to combine.
1/4 cup plain bread crumbs, 1/2 cup milk, 1 pound ground beef, 2 Tablespoons chopped flat-leaf parsley, 1/2 teaspoon onion powder, 1/2 teaspoon garlic powder, 1/2 teaspoon dried basil, 1/2 teaspoon dried oregano, 3/4 teaspoon kosher salt, 1/4 teaspoon freshly ground black pepper, 1/2 cup freshly grated Parmigiano-Reggiano cheese, 1 large egg
Divide into 2 tablespoon size meatballs. Add a cube of mozzarella in the center of each meatball and shape into a ball. Repeat with remaining mozzarella cheese and meat.
4 ounces mozzarella cheese
Heat olive oil in a large saucepan over medium heat. Add onion and saute for 5 minutes. Add garlic and cook another 30 seconds. Add tomatoes, basil, oregano, salt and pepper. Simmer over low heat for 15 minutes, stirring occasionally.
1 medium onion, 1 Tablespoon olive oil, 4 cloves garlic, 2 28-ounce cans crushed tomatoes, 1/2 teaspoon dried basil, 1/2 teaspoon dried oregano, Salt & pepper
Add the meatballs to the sauce. Simmer and cook, turning the meatballs partway if they aren't completely covered in sauce, until the meatballs are cooked through.
Meanwhile, cook the spaghetti noodles in a large pot of salted, boiling water according to package directions until al dente (typically around 8-10 minutes).
1 pound spaghetti
Drain and toss the spaghetti with the meatballs and sauce, then sprinkle with additional Parmigiano-Reggiano cheese and chopped parsley to serve.