Pat chicken dry with paper towels and place breast-side-down on a large cutting board. Using sharp kitchen shears, remove the backbone by cutting along either side of it. Turn chicken over and lay out flat. Press firmly on breast to flatten the chicken. For added stability, run a metal or wooden skewer horizontally, entering through one thigh, going through both breast halves, and exiting through the other thigh. Tuck wing tips behind back. Season generously with salt and pepper.
Place chicken skin-side up on cooler side of grill with legs facing towards hotter side. Cover grill with vents on lid open and aligned over the chicken. Open bottom vents of grill if using a charcoal grill. Cook until instant read thermometer inserted into deepest part of breast registers 110°F.
43 grader C
Carefully flip chicken and place skin-side-down on hotter side of grill with breasts pointed towards cooler side. If using a gas grill, reduce heat to medium-low. Press down firmly with a wide, stiff spatula to ensure good contact between bird and grill grates. Cover and cook until skin is crisp and instant read thermometer inserted into deepest part of breast registers 145 to 150°F,
62-65 grader C
about 10 minutes longer. If chicken threatens to burn before temperature is achieved, carefully slide to cooler side of grill, cover, and continue to cook until done. Do not leave the lid off for longer than it takes to check temperature.
Transfer chicken to a cutting board and allow to rest for 5 to 10 minutes. Carve and serve.