Pour about 1/3 of the water into a large pot (sized to accommodate the brine and submerged chicken) with the remaining brine ingredients.
Bring to a boil for 1 minute, stirring to dissolve the salt. Remove from heat and pour in the remaining water.
Allow the mixture to cool completely before use (approximately 30 minutes, followed by 1 1/2 hours of refrigeration). DO NOT place the chicken in the brine before it has fully cooled, as this poses a health hazard.
Flip the chicken upside down (so the legs and breast are on the underside) and submerge it in the brine. Cover and refrigerate for 12-24 hours.
Roasting Brined Chicken
Remove the Roaster from the brine and pat it dry to eliminate excess moisture.
Tie the legs with string (if desired) and tuck the wings under. Drizzle or brush most of the butter all over, including the underside (the butter will firm up on contact).
Sprinkle with pepper and a pinch of salt, then place the chicken on a rack in a heavy-based roasting tray. Set aside for 20 minutes.
Preheat the oven to 430°F.
Turn down the oven to 350°F, then roast the chicken for 50 minutes to 1 hour or until the internal temperature at the joint between the leg and thigh is 165°F, or until the juices run clear.
Check at 45 minutes, rotate the pan if browning is uneven, and brush the top with the remaining melted butter.
Remove the chicken from the roasting tray, cover loosely with foil, and let it rest for 10 to 15 minutes before carving.