Bring a large pot of salted water to a boil. Add spaghetti noodles and cook until just al dente (about 1–2 minutes less than package directions). Drain and set aside.

In a large skillet or Dutch oven, heat olive oil over medium-high heat. Add ground beef and cook, breaking it apart with a spatula, until browned and no longer pink. Drain excess grease if needed.

Stir in the diced onion and cook until softened, about 3–4 minutes. Add garlic and cook for another 30 seconds. Sprinkle in taco seasoning and stir well.

Pour in diced tomatoes, tomatoes with green chilies, beef broth, and tomato sauce. Stir and bring to a gentle boil.

Add the drained spaghetti to the sauce. Reduce heat to low, toss to coat the pasta evenly, and let it simmer for 3–4 minutes so flavors meld.

Stir in sour cream and half of the shredded cheese until melted and creamy.

Sprinkle the remaining cheese on top, cover, and let sit for 1–2 minutes until melted. Garnish with your favorite toppings and serve hot.