To achieve incredibly crispy skin on a roast chicken, thoroughly dry the skin, rub it generously with oil or fat, season liberally with salt, roast at a high initial temperature, and ensure it cooks on a rack in a single layer without basting.
Achieving that coveted crackly, golden-brown skin on a roast chicken is a multi-step process centered on moisture removal and heat application. First and foremost, the chicken skin must be as dry as possible. Pat the entire chicken, inside and out, exceptionally well with paper towels. For best results, you can even refrigerate the chicken, uncovered, for several hours or overnight; this allows the skin to air-dry thoroughly. Next, rub the dried skin generously with a high-smoke-point oil (like olive, avocado, or vegetable oil) or melted butter. This fat not only helps conduct heat but also promotes browning and crisping. Liberally season the skin with salt; salt draws out remaining moisture and contributes significantly to crispness. Start roasting the chicken at a high oven temperature, typically 425-450°F (220-230°C), for the first 15-20 minutes to jump-start the crisping process, then reduce the temperature to finish cooking. Always place the chicken on a roasting rack set within a pan; this elevates the chicken, allowing hot air to circulate completely around it and preventing a soggy bottom. Finally, avoid basting if crispy skin is your priority, as re-wetting the skin will prevent it from crisping.
Consider spatchcocking the chicken (removing the backbone and flattening it) as it exposes more skin surface to direct heat, promoting superior crisping.