Preheat the oven to 400ºF (205ºC).
Place the chicken in a baking dish and drizzle with the oil and season with salt and pepper. Sprinkle the parsley and dill over the chicken and rub generously into the chicken. Transfer to the oven and bake for 20 to 25 minutes or until completely cooked through. Let cool slightly and then slice.
In a large bowl, combine the romaine, sliced chicken, bacon, onion, and tomatoes. Pour the ranch dressing over top and toss to combine. Add the avocado and gently toss.
Divide between bowls and enjoy!