An hour before cooking, remove chicken from fridge and dry with paper towels. Combine tandoori paste and yoghurt then rub all over chicken skin.
Preheat oven to 200°C. To make pilaf, heat oil and butter in a large frying pan (with a lid) on medium heat. Add onions and a pinch of salt and cook for about 8 minutes or until lightly golden. Add garlic and spices and cook for 1 minute. Add rice and stir to combine. Add stock and ginger and bring to boil. As soon as it boils, cover, reduce to the lowest heat and simmer for 12 minutes. Turn off heat and steam, still covered, for a further 10-12 minutes. Do not lift lid at any stage during simmering and steaming.
Remove cinnamon quill from pilaf then use a spoon to stuff pilaf into chicken cavity (take care to avoid cross-contamination from raw chicken, so you can serve any leftover pilaf in a bowl). Cross legs and secure with baking string. Tuck in wing tips to prevent them burning. Place, breast-side up, in a large baking dish. Sprinkle with the flaky sea salt and squeeze over the lemon juice.
Roast chicken for about 50 minutes, until cooked through and juices run clear when flesh is pierced. Rest for 10-15 minutes before carving. Serve with warmed additional pilaf on the side. This dish goes beautifully with maple curry roasted baby carrots (see below).