Prepare the Chicken: Preheat the oven to 425°F (220°C). Pat the chicken dry with paper towels. Rub the chicken all over with olive oil and softened butter. Season generously with thyme, rosemary, garlic powder, paprika, salt, and pepper.

Prep the Vegetables: In a large bowl, toss the carrots, parsnips, sweet potato, and onion with olive oil, salt, and pepper. Spread the vegetables evenly on the bottom of a roasting pan.

Assemble the Dish: Place the seasoned chicken on a rack or directly on top of the vegetables in the roasting pan. If using, pour chicken broth or water into the pan for added moisture.

Roast: Roast the chicken and vegetables in the preheated oven for 1 hour and 15 minutes to 1 hour and 30 minutes, or until the internal temperature of the chicken reaches 165°F (74°C) in the thickest part of the breast. Baste the chicken with pan drippings every 20-30 minutes for added flavor and moisture.

Rest and Serve: Remove the chicken from the oven and let it rest for 10-15 minutes before carving. Toss the roasted vegetables in the pan drippings for extra flavor and serve alongside the chicken.