Preheat oven to 375°F (190°C). Lightly grease a baking dish.
Place chicken breasts in the dish and drizzle with olive oil.
Season with oregano, garlic powder, salt, and pepper.
Sprinkle feta cheese, olives, and sun-dried tomatoes evenly over the chicken.
Bake uncovered for 25-30 minutes, or until chicken is cooked through and reaches an internal temperature of 165°F (74°C).
Garnish with fresh parsley before serving if desired.