Preheat oven to 425 degrees. Spray a 13 by 9-inch baking dish with non-stick cooking spray.
Pound chicken with the flat side of a meat mallet to even out thicker portions and to help tenderize.
In a small bowl whisk together garlic powder, thyme, onion powder, oregano, paprika, chili powder, 3/4 tsp salt (or to taste) and 1/2 tsp pepper.
Place chicken in baking dish, brush both sides with olive oil.
Season both sides of chicken evenly with the spice mixture.
Bake in preheated oven until center of chicken breasts registers 165 on an instant read thermometer, about 16 - 20 minutes.
Remove from oven and let rest 5 minutes before serving and slicing. Garnish with parsley if desired.