In a large pot, combine ground beef, chopped onion, garlic, salt, and black pepper. Cook over medium heat, stirring and breaking up the beef until browned and onions are softened, about 8 minutes.
Add canned crushed tomatoes, tomato paste, and Italian seasoning to the pot. Stir well to combine.
Bring the sauce to a gentle simmer.
Form the browned ground beef mixture into small meatballs directly in the pot, distributing them evenly over the sauce.
Add spaghetti pasta to the pot, pushing it down gently into the sauce so it is mostly submerged.
Cover and simmer on low heat for 20-25 minutes, stirring occasionally to prevent sticking, until pasta is tender and meatballs are cooked through.
Adjust seasoning with additional salt and pepper if needed.
Serve the spaghetti and meatballs in shallow white bowls, ensuring meatballs are evenly distributed over the pasta and sauce.
Sprinkle grated Parmesan cheese and a few visible Italian herbs over the top for a rustic finishing touch.