Preheat oven to 400°F (200°C) and line or lightly grease a baking sheet.
In a medium bowl, mix shredded chicken, cheese, onions, green chilies, cumin, garlic powder, chili powder, salt, and pepper.
Warm tortillas 15–20 seconds in microwave to make pliable.
Place 2–3 tablespoons of chicken mixture on one end of each tortilla and roll tightly; place seam-side down on the baking sheet.
Lightly brush or spray rolled taquitos with olive oil.
Bake for 18–22 minutes, turning halfway through, until golden and crispy.
Let cool for a few minutes and serve with optional toppings like sour cream, guacamole, salsa, or cilantro.