Place the oven rack in the lower third position. Preheat to 475°F (246°C).
In a large 12-inch cast iron skillet, add the onions, celery, carrots, 1 tablespoon olive oil, ½ teaspoon salt, and ¼ teaspoon pepper. Stir the ingredients to combine. Spread them out in an even layer, and add 5 sprigs of thyme and 3 sprigs of rosemary on top.
Remove the neck and giblets from the cavity of the chicken, discard. Thoroughly dry the surface and cavity of the chicken with paper towels. Removing excess moisture helps the skin crisp quicker instead of steaming.
Season the cavity with ½ teaspoon salt and ¼ teaspoon pepper, add 4 cloves of crushed garlic, 5 sprigs of thyme, and 2 sprigs of rosemary. Massage the inside of the bird to infuse it with the flavors.
Truss the chicken using about 3 feet of cooking twine. Tuck the wings behind the chicken’s back. Place the chicken on it’s back and legs facing towards you. Place the string under the neck area then gather the two ends so that it runs along the sides of the wings and body, and then cross the string at the crown (tip of the breast). Tie the string in a knot, this should plump up the breasts. Gather the legs and tie them together with the string.
Melt 2 tablespoons of butter. Place the chicken breast-side up and brush with a third of the butter, then generously season with salt and pepper. Flip the chicken over and brush with butter, then season with salt and pepper. Save the remaining butter to baste the chicken later.
Place chicken breast-side down on top of the vegetables. Transfer to the oven and roast for 30 minutes.
Remove the chicken from the oven. With the cavity facing away from you, carefully flip the chicken breast-side up using paper towels. Brush the surface with the remaining melted butter. Make sure that the oven gets back to about 475ºF (246°C) to ensure that the skin properly browns.
Roast the chicken for 25 to 30 minutes, or until the temperature registers between 160 to 165°F (71 to 74°C) in the breast, and 165 to 170°F (74 to 77°C) in the meatiest portion of the thigh. If needed, return the bird to the oven for more roasting, and check every 5 minutes. Transfer the chicken to the cutting board and let it rest for 20 minutes before slicing.
Gravy
Discard the thyme and rosemary. Transfer the roasted vegetables to a bowl or serving platter. Pour the pan juices into a fat separator and let it sit until the layers separate. Pour only the liquid juices into a measuring cup. Add enough chicken stock or broth to reach 1 cup of total liquid.
In the same skillet used to roast the chicken, make the gravy. Alternatively, use a clean large skillet. Heat 1 tablespoon of butter and 1 tablespoon of flour over medium heat. Once the butter melts, whisk until the flour mixture turns pale yellow, about 1 minute.
Gradually whisk in 1 cup of the defatted pan juices and stock mixture, until the sauce lightly thickens, about 2 to 4 minutes. Season with salt and pepper to taste. Place a fine meshed strainer on top of a medium bowl and strain the sauce.
To Serve
Slice the chicken and serve with roasted vegetables and gravy.
Notes
Pan Selection: A roasting pan can be used instead of a cast iron skillet. The gravy can be made in the pan on the stovetop, or use a clean skillet.
For Thicker Gravy: Use 2 tablespoons butter and 2 tablespoons flour with 1 cup of juices/stock.