Cook the Pasta:
Cook the spaghetti according to the package instructions. Drain and set aside.
Prepare the Taco Meat:
In a large skillet, heat a little oil over medium heat. Add the chopped onion and sauté until soft, about 2–3 minutes. Add the ground beef (or turkey) and cook until browned, breaking it up as it cooks. Drain any excess fat.
Season the Meat:
Add the taco seasoning, diced tomatoes, green chilies, and broth to the skillet with the cooked meat. Stir well and bring to a simmer. Let it cook for about 5–7 minutes, allowing the flavors to meld and the sauce to thicken. Season with salt and pepper to taste.
Combine with Pasta:
Add the cooked spaghetti to the skillet with the taco meat mixture and stir to combine. You can also transfer the meat and pasta mixture to a 9x13-inch baking dish if you prefer to bake it.
Top with Cheese:
Sprinkle the shredded cheddar cheese over the top of the pasta mixture. If baking, place the dish in a preheated 350°F (175°C) oven for 10–15 minutes, or until the cheese is melted and bubbly.
Garnish and Serve:
Once the dish is ready, garnish with sour cream, green onions, sliced olives, and fresh cilantro, if desired. Serve hot and enjoy!