Place the basmati rice in a large bowl and cover with cold water; soak for 30 minutes, then rinse under cold water until it runs clear and drain well.
Preheat the oven to 160°C (325°F).
Heat 3 tablespoons olive oil in a 30cm ovenproof casserole over medium heat. Add the chicken pieces and sauté until golden brown; remove and set aside.
Reduce heat to low and add the butter. Add the chopped onion, grated carrot, cinnamon quill, star anise, and thyme stalks; cook, covered for most of the time, until the onion is translucent, about 5 minutes.
Add ground cumin, turmeric, smoked paprika, chilli flakes and crushed garlic; cook 1 minute until fragrant.
Deglaze the pan with 1/2 cup fresh orange juice, scraping up any browned bits. Stir in the orange marmalade and cook until most of the liquid has evaporated.
Add the drained rice and toss to coat in the spiced mixture for about 1 minute.
Pour in the hot chicken stock and add the orange zest. Increase heat to medium–high and bring to a rolling boil; cook for exactly 2 minutes after boiling begins.
Return the browned chicken to the casserole and gently toss to distribute. Cover with the lid and transfer to the preheated oven; bake for 25 minutes.
Remove from oven and let rest, covered, for 5 minutes. Remove the cinnamon, star anise and thyme stalks. Fluff the rice with a fork, sprinkle with chopped parsley and optional toasted nuts, and serve hot.