Place the potatoes, carrots, radishes, garlic, lemon zest, lemon juice, lemon slices, rosemary, and parsley into a bowl.
Drizzle olive oil over the vegetables and mix until they are evenly coated.
Season with salt and pepper to taste.
Pour the vegetables into a 9x13-inch pan, and spread them out into a single layer.
Cover the pan with foil and bake for approximately 30 minutes.
If desired, spread softened butter under the chicken skin. Spread a light layer of butter on the outside of the chicken skin, and season with salt and pepper.
Remove the vegetables from oven, remove the foil, and place the chicken over the vegetables, skin side up.
Roast the chicken uncovered at 425°F for approximately 30 minutes or until done. The chicken is done when it is pierced and the juices run clear and it has an internal temperature of 165°F.