Heat the oven to 425°F and place the halved potatoes in a large oven-safe skillet or roasting pan.
Toss the potatoes with half of the olive oil, salt, pepper, and smoked paprika, then roast for 20 minutes.
Whisk the maple syrup, Dijon mustard, whole-grain mustard, garlic, and remaining olive oil together.
Season the chicken, add it to the hot pan with the potatoes, and brush generously with the maple mustard sauce.
Roast for 18 to 22 minutes, brushing once more, until the chicken reaches 165°F and the potatoes are tender.
Rest for 5 minutes, spoon pan juices over the chicken, and finish with parsley if using.