Preheat the oven to 425 degrees Fahrenheit. Remove the giblets from 1 (5-pound) whole chicken. Season the outside of the chicken generously with salt and pepper. Place the chicken in a roasting pan or large cast iron skillet.
Stuff the inside cavity of the chicken with 1 medium quartered onion , 1 sprig fresh rosemary, and 1 medium quartered lemon.
In a small bowl, add 1 cup softened unsalted butter , 3 cloves minced garlic, 1 tablespoon finely chopped thyme , 1 tablespoon finely chopped oregano, 1 tablespoon finely chopped rosemary , 1 teaspoon salt, and ½ teaspoon black pepper. Stir until combined and rub the herb butter evenly on the outside of the chicken.
In a medium-sized bowl, add 1 large quartered onion, 1 pound baby potatoes, 3 large sliced carrots1 tablespoon olive oil, and salt and pepper. Stir to combine and layer the vegetables around the chicken in the roasting pan.
Roast the chicken for 1 ½ hours or until the internal temperature reaches 165 degrees Fahrenheit.