Spread the oil on the bottom of a large cast iron skillet or Dutch oven. Add the chicken and season with paprika.
In a medium bowl, whisk together the mustard, maple syrup, vinegar, and salt. Spoon 1/3 of the sauce over the chicken thighs.
Place chicken in the oven and bake for 10 minutes. Remove the skillet from the oven and spoon half of the remaining sauce over top, add the sweet potatoes. Return the skillet to the oven and continue baking for 10 minutes.
Remove the skillet from the oven and spoon the remaining sauce over top. Add the Brussels sprouts. Return the skillet to the oven and continue baking for 20 minutes or until the potatoes and Brussels sprouts are fork-tender.
Remove from the oven and serve immediately.
Notes
STORE leftover Maple Mustard Chicken in an airtight container in the refrigerator for up to 4 days. You can also FREEZE it for up to 4 months.To REHEAT, place it in a preheated oven at 350°F (175°C) for 15-20 minutes, or microwave until heated through. If reheating from frozen, thaw in the refrigerator overnight before reheating.