Marinade: In a small bowl combine chipotle paste, olive oil, sugar, lime zest, smoked paprika, cumin, oregano, garlic, salt and pepper.
Remove Back Bone: Pat chicken dry with paper towels. Flip the chicken breast side down and use a pair of kitchen shears cut through the ribs directly either side of the back bone. You can either start at the neck or the butt, just go nice and close to the back bone so you don't remove too much of the chicken. Completely remove backbone (you can use this another time for stock) and pull open up the chicken.
Flatten Chicken: Gently open up the rib cage and slice along the sternum. This will help the breast bone pop out (not crucial, but does help. See video below if you're not sure where this is). Season the inside with a pinch of salt and pepper. Trim off excess skin, then flip over and firmly push down the breasts to flatten the chicken. Tuck wings under chicken.
Coat Chicken: Grab a spoon and begin loosening the skin from the meat all across the breasts and legs. You can also loosen it around the wings too with a smaller spoon. Be firm, but still be careful not to rip the skin. Spread most of the marinade underneath the skin, ensuring you evenly distribute it and spread it to all parts of the chicken. Spread a dollop on top and any of the remaining oil that separated. Cover and marinate for as long as you have time for (preferably 2hours+). Bring close to room temp again before roasting.
Tray Bake: Combine peppers, potato, onions and corn on a large roasting tray with a drizzle of olive oil and a good pinch of salt and pepper. Stand up the corn on the cob halves in the centre to create a small platform for the chicken (see notes). Place chicken on corn, making sure the chicken is sturdy (so it won't fall during roasting) and also making sure it is completely level (so it cooks evenly).
Roast: Drizzle the chicken with a little more oil and coat with a good pinch of salt and pepper. Place in the oven at 425F/220C for 45mins. The internal temperature should be 75C/165F with the juices running clear when pierced at the join between the drumstick and the body.
Serve: Carefully transfer chicken to large plate or board and allow to rest for 15mins. This will ensure the chicken retains its juices. Remove veg from tray and drizzle a splash of hot chicken stock. Use a plastic spatula to scrape off all the gorgeous flavour. Dice up chicken as you wish and serve with veg and pan juices.