Prepare the Marinade: In a large bowl, combine the buttermilk, garlic, salt, black pepper, paprika, thyme, rosemary, onion powder, and cayenne pepper. Mix well.

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

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

Prepare for Roasting: Remove the chicken from the marinade and let any excess drip off. Discard the marinade.

Season the Chicken: Rub the chicken with olive oil and sprinkle additional salt and pepper on the skin for extra flavor and crispiness.

Roast the Chicken: Place the chicken in a roasting pan, breast side up. Roast in the preheated oven for 1 hour, or until the internal temperature reaches 165°F (75°C) and the skin is golden brown.

Rest the Chicken: Once cooked, remove the chicken from the oven and let it rest for 10-15 minutes. This allows the juices to redistribute, ensuring a moist chicken.

Carve and Serve: Carve the chicken into pieces and arrange them on a platter. Garnish with fresh herbs if desired.