Cut the mushrooms in half and set them aside.
Heat the ghee in a large, heavy-based pan over medium heat, add the whole spices, and stir-fry for 1-2 minutes, or until they start to change color. Add the boiled onion paste and stir-fry for 2 minutes, then add the ginger and garlic pastes and stir-fry for 30 seconds.
Add the ginger and green chillies and stir-fry for a further 30 seconds, then add the chilli powder, ground mace, and coriander and stir-fry for 30 seconds.
Remove the pan from the heat and stir in the yoghurt. Season with salt, then return to the heat, pour in 125ml / 4 1/2fl oz (1/2 cup) water, and bring to a boil. Reduce the heat and simmer for about 2-3 minutes, or until the oil has separated out.
Add the mushrooms and simmer for a further 2 minutes, before adding the spring onions and simmering for 1 minute. Remove the pan from the heat and adjust the seasoning, if necessary.