Boil a large pot of salted water, add spaghetti, and cook for 8-10 minutes until al dente. Reserve pasta water before draining.

Chop fire-roasted hatch chiles, dice onion, and mince garlic.

Heat olive oil in a skillet over medium heat. Sauté onion for 3-5 minutes until soft, then add garlic and sauté for another minute.

Stir in hatch chiles, vegetable broth, sea salt, and chili powder. Simmer for 3-5 minutes until slightly thickened.

Reduce heat to low, stir in shredded Monterey Jack cheese and sour cream until creamy. Adjust consistency with reserved pasta water if needed.

Add drained spaghetti to the skillet and toss to coat with the sauce. Let sit for 1 minute to allow flavor absorption.

Serve in bowls and garnish with cilantro and cotija cheese. Add chili powder on top if desired.