Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package instructions until al dente. Drain and set aside.

In a skillet, heat the olive oil over medium heat. Add the chopped onion and garlic, saut? until softened.

Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned and no longer pink.

Stir in the diced tomatoes, Italian seasoning, salt, and pepper. Simmer for about 15 minutes, allowing the flavors to meld.

Add the cooked spaghetti to the meat sauce, tossing to combine. Serve hot, topped with grated parmesan cheese.