Heat oil in a large pot or Dutch oven over medium-high; cook onion 3-4 minutes until softened.
Brown beef 5-7 minutes, breaking up with a spoon, until no pink remains; drain excess fat if needed.
Add taco seasoning; cook 1 minute until fragrant.
Add uncooked pasta, broth, tomatoes with chiles and juices, and canned chiles; stir and bring to a boil.
Reduce heat to medium-low; cover and simmer 12-15 minutes, stirring occasionally, until pasta is tender and most liquid absorbed.
Off heat, stir in sour cream and 1½ cups cheese until melted and creamy.
Top with remaining cheese and favorite taco toppings; serve immediately.