In a large skillet, heat olive oil over medium heat. Add the chopped onion and cook for 3-4 minutes, until softened.
Add the minced garlic and cook for another 30 seconds until fragrant.
Stir in the shredded chicken, cumin, chili powder, salt, and pepper. Add the diced green chilies and mix well. Cook for 2-3 minutes to combine the flavors.
Remove from heat and stir in the shredded Monterey Jack cheese and cilantro (if using). Set aside.
