In a small bowl, whisk together salt, pepper, garlic powder, onion powder and chili powder. Place the chicken in a baking dish and sprinkle the seasoning mixture over both sides of the chicken and rub it in with your hands.
Heat olive oil in a large skillet (with a tight fitting lid) over medium-high heat. Add chicken and leave it alone to sear and cook for 4 minutes on the first side. Flip the chicken and add the butter to the skillet, swirling it around the pan as it melts. Cook for 2 minutes, then cover the skillet with a tight fitting lid. Turn heat down to low for 10 minutes. Remove the skillet from heat and rest, covered, for another 5-10 minutes.
Serve immediately with parsley garnish, if desired.