In a large bowl, combine the buttermilk, salt, black pepper, garlic powder, onion powder, paprika, thyme, and smoked paprika. Whisk until well mixed.

Place the whole chicken in a large resealable plastic bag or a deep dish. Pour the buttermilk marinade over the chicken, ensuring it’s well coated. Seal the bag or cover the dish and refrigerate for at least 4 hours, preferably overnight.

When ready to cook, preheat your oven to 425°F (220°C).

Remove the chicken from the marinade and let the excess drip off. Discard the marinade. Pat the chicken dry with paper towels to ensure crispy skin.

In a small bowl, mix the olive oil or melted butter with a bit of salt and pepper. Rub this mixture all over the chicken, ensuring even coverage.

Place the chicken breast-side up on a roasting rack in a roasting pan. Roast in the preheated oven for about 1 hour, or until the internal temperature reaches 165°F (74°C) and the skin is golden brown and crispy.

Once cooked, remove the chicken from the oven and let it rest for 10-15 minutes before carving.

Carve the chicken into serving pieces, garnish with fresh herbs if desired, and serve it warm.