Start by cooking the pasta according to the package instructions.
In a large pan, cook the ground beef and onion over medium-high heat until browned. Drain off any excess grease.
Add the garlic and taco seasoning to the pan, and cook until fragrant, about 1 minute.
Stir in the diced tomatoes, green chilies, beef broth, Worcestershire sauce, and soy sauce. Bring the mixture to a boil, then reduce heat and simmer for 5 minutes.
Turn off the heat, and stir in the shredded cheese until melted and creamy.
Season the sauce with salt and pepper to taste.
Add the cooked and drained spaghetti to the pan, and toss until well coated in the sauce.
Garnish with chopped cilantro, if desired, and serve hot.