Directions

• Place chicken, breast side down, on a cutting board. Using poultry shears, cut along both sides of backbone; remove and discard backbone. Turn chicken, breast side up, and open underside of chicken like a book. Using the heel of your hand, press firmly against the breastbone until it cracks. Tuck wing tips under chicken. Pat chicken dry.
• Sprinkle chicken evenly with salt. Place on a wire rack placed inside a rimmed baking sheet. Refrigerate, uncovered, for at least 12 hours or up to 36 hours.
• Stir together brown sugar, black pepper, cumin, garlic, onion, and cayenne in a small bowl. Gently blot chicken skin to remove excess moisture. Rub chicken evenly with olive oil. Sprinkle spice mixture evenly over chicken. Set chicken aside at room temperature while preparing smoker.
• Prepare charcoal fire in smoker according to manufacturer's instructions, bringing internal temperature to 275°F. Maintain temperature inside smoker until smoke is burning cleanly, 15 to 20 minutes. Place hickory chunks on coals, and set an empty drip pan underneath grates. Place chicken on grates, breast side up, and close lid. Smoke, undisturbed, for 1 hour, 30 minutes, maintaining temperature at 275°F. Gently baste chicken with melted butter. Smoke for 15 more minutes, and baste once more with butter. Smoke until a thermometer inserted into thickest portion of breast registers 165°F and thigh registers 175°F, 15 to 45 more minutes.
• Transfer chicken to a cutting board, and let rest for 15 minutes. Carve as desired, and serve.