First take a deep broad pan and grease with ghee.
Put some chopped mint and coriander leaves along with few birista (crisp fried onions).
Then put all the cooked mushrooms in even layer followed by some more birista.
Next put all the cooked rice and gently spread all over.
Add kewra water / rose water with the soaked saffron and pour over the rice (here and there).
Again top with some birista, chopped mint & coriander leaves, 1-2 pinch of biryani masala powder, fried cashews & raisins and few drops of ghee.
Cover the pan and place over a hot tawa or griddle.
Cook for 25-30 minutes over low heat.
Turn off heat and gently fluff the biryani.
Serve along with raita of your choice !