Pre-heat an oven to 180°C.
Heat the oil and then temper the cinnamon, cardamom, fennel, cumin and bay leaves in a pan. Now add the onions and fry till they turn golden, using a pinch of salt to help them sweat. Add the ground cumin, coriander and chilli.
Continue to stir adding a small amount of water to prevent the spices from burning.
Add the tomato purée, and the chopped tomato with some sugar to balance the acidity.
Gradually add the yoghurt and stir into the mixture. Keep stirring till all the yoghurt has incorporated into the sauce and the oil has separated.
Sear the meat in some oil in a frying pan, ensuring that it is sealed and browned all over.
Place in an oven roasting tray, then pour over the sauce, cover with foil and then roast in the oven for four hours until the meat is tender.
Remove from the oven, add the Garam Masala, adjust for seasoning and then garnish with butternut crisps and fresh coriander.
To make the Garam Masala, lightly toast all ingredients, in a dry frying pan till they release their aroma (except the rose petals). Allow to cool, and then grind together with the rose petals. Keep in a sealed jar until needed.