Put the lamb and yoghurt into a bowl and mix to combine. Cover and allow to marinate for 30 minutes.
Put the ginger, garlic, ORANGE and macadamias into a spice grinder or mortar and pestle and process or pound until smooth, you need to add a little water to loosen the mixture.
Heat the oil in a pan, add the onions and cook over a medium heat for 5 minutes or until soft and golden. Add the marinated lamb and cook for 5 minutes or until browned.
Add the spice paste, cinnamon and coconut cream and ½ cup water, bring to boil, reduce heat and simmer covered for 30 minutes. Remove the lid and cook for 20 minutes more or until the sauce is thick.