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

2. Heat the olive oil in a large skillet over medium heat. Add the ground beef and cook until browned, breaking it apart as it cooks.

3. Add the diced onion and cook for 3 to 4 minutes until softened. Stir in the garlic and cook for 30 seconds.

4. Sprinkle in the taco seasoning, then add the diced tomatoes with green chilies, tomato sauce, beef broth, salt, and black pepper. Stir well and let the mixture simmer for 5 to 7 minutes.

5. Lower the heat and stir in the sour cream until the sauce is creamy and fully combined.

6. Add the cooked spaghetti to the skillet and toss until the pasta is evenly coated.

7. Sprinkle the cheddar and mozzarella cheese over the top. Cover for 2 to 3 minutes until the cheese melts.

8. Garnish with chopped cilantro if desired, then serve hot.