Preheat oven to 425 degrees F. Pat chicken dry and season with salt and pepper. Place in a large cast iron skillet. Place fennel around the chicken. Drizzle with ¼ cup olive oil.
Roast chicken about 40 minutes to an hour, until an instant-read thermometer inserted into the thickest part of the breast and thigh reads 160 degrees F. Transfer the fennel to a large bowl and the chicken to a cutting board. Let it rest for 15 minutes.
In a small bowl, whisk 2 tablespoons of olive oil with the lemon juice. Stir in the dates, olives, and parsley. Season with salt and pepper.
Add the orange to the bowl with the fennel and gently toss. Serve chicken with citrus-fennel salad. Drizzle the date-olive dressing over top.