Preheat the oven to 400°F (200°C).
Whisk together the olive oil, Dijon mustard, lemon juice, lemon zest, oregano, thyme, smoked paprika, garlic, salt, and pepper.
Coat the chicken thoroughly with the marinade and let it rest for at least 20 minutes.
Arrange the potatoes, onion, olives, and lemon slices in a large Dutch oven or baking dish.
Place the chicken on top and pour over the remaining marinade.
Roast uncovered for 45–55 minutes, until the chicken reaches 165°F (74°C) and the potatoes are fork-tender.
Broil for 2–3 minutes for extra crispy skin, if desired.
Garnish with fresh parsley and serve immediately with the pan juices spooned over the top.