Preheat oven to 240C.
Butterfly the chicken by placing it on a chopping board, breast side down, and with sharp kitchen scissors cutting down either side of the backbone and removing it. Turn the bird over and press down firmly with the palms of your hands to flatten it, then gently separate the skin and flesh over the breasts with your fingers creating two pockets. Keep the backbone to use when making broth or stock.
Squeeze the lemon juice all over the chicken and carrots.
Stir together the softened butter, spices, salt and pepper and rub this mixture all over the carrots and the chicken, pushing some into each pocket.
Place the chicken in a large baking dish with the carrots around it, then put the dish into the oven, immediately reducing the temperature to 125C. Roast for 2 hours, basting occasionally with the pan juices.
If you would like to brown the chicken skin a little more, turn on the oven grill to low-medium and place the baking dish in the centre of the oven, not too close to the griller so it doesn't burn. Grill for approximately 3-5 minutes or until it is browned to your liking.
Take the chicken out of the oven and rest for 5 minutes, then cut it into pieces.
Drizzle the chicken with olive oil, scatter over the parsley, mint and nuts, and serve with yoghurt, lemon wedges and green salad or steamed green veggies.