Preheat the oven to 425°F (220°C).
In a small vessel, combine the paprika, dried basil, dried thyme, dried oregano, dried parsley, salt, and black pepper to form an even spice rub.
Coat both sides of the chicken breasts with olive oil, then apply the dried spice blend uniformly over the surface of the meat.
Place the seasoned chicken in an oven-safe baking dish and roast for 20 to 25 minutes, turning the breasts over halfway through cooking, until the internal temperature reaches 165°F (74°C).
Transfer the roasted chicken to a cutting board and let rest for 5 minutes before carving into thin slices.
In a large bowl, combine the diced cucumber, cherry tomatoes, green bell pepper, red onion, kalamata olives, and feta cheese.
Pour the Greek salad dressing over the salad ingredients and toss gently until thoroughly combined.
Divide the salad mixture evenly across 4 plates, top each serving with sliced chicken breast and one-fourth of the diced avocado, and serve.