Preheat your oven to 230 C. Pour the olive oil in a 9x13 baking dish.
Place chicken in the baking dish and move them around to coat them with oil on both sides.
In a small bowl, add the salt, pepper, onion, garlic, and chili powders, mix together. Sprinkle mixture on both sides of the chicken, rubbing it in with your fingers for each side. Arrange the chicken in a single layer side by side.
Bake for 15 to 20 minutes or until juices run clear. If the chicken is large and thicker, it may take longer.
Remove from oven and cover with foil to rest for 5 to 10 minutes, the chicken will absorb some of the juices during this time.
Serve with mashed potatoes, pasta, or rice, and a vegetable for a complete meal.