Step 1

Add 3 cups of the cold water to a large Dutch oven or pasta pot. Pour in the salt, sugar, and peppercorns. Bring to a boil over high heat, stirring until the salt and sugar dissolve, and then turn off the heat.

Step 2

Meanwhile, add 2 cups of the water to a high-powered blender or food processor. Working in batches as needed, add the onions, leeks, carrots, celery, bay leaves, thyme, and rosemary.

Step 3

Purée until liquefied.

Step 4

Add the ice to the pot along with the remaining 6 cups of cold water. Stir until the ice cubes melt and the water is cold. Add the puréed ingredients. Submerge the chicken, cover the pot, and refrigerate for 24 hours.

Step 5

Preheat the oven to 425°F (218°C). Place a rack in a roasting pan.

Step 6

Rinse the chicken and pat dry with paper towel. Discard the brine.

Step 7

Place the bird on the rack in the pan and tie the legs together with kitchen twine, if desired. Brush with the melted butter and season generously with pepper. Roast (middle rack) for about 1 hour and 10 minutes, or until an instant-read thermometer inserted into the thigh meat (away from the bone) registers 165°F (74°C). The skin should be brown and crisp. If it starts to overbrown, loosely cover with a large sheet of aluminum foil.

Step 8

Let the chicken sit, loosely tented with aluminum foil, for 15 minutes before carving.