To make the biriyani masala, dry roast all the ingredients (under the heading For my special Kolkata biriyani masala) till they release their fragrant aroma. Cool and grind to a fine powder. Keep aside.
Marinate the chicken pieces with onion paste, ginger-garlic paste, whipped curd, turmeric powder, red chili powder, a hint of salt and 1 tbsp of biryani masala. Refrigerate for at least 30 minutes.
In the meantime, soak the basmati rice for 20 odd minutes. Drain the water.
Cook the rice now in boiling water, just a few drops of oil added to the water, till about 70% done. Drain the water. Spread the cooked rice on a flat dish and keep aside.
Heat oil in frying pan, shake off the marinate and lightly sear the chicken high flame. Add the marinade now and cook over a low flame till about 70% done. If its getting a bit too dry, splash a little water in between.
Soak the saffron strands in warm milk. Keep aside.
Now to assemble the biriyani, take a deep bottomed pan, grease with ghee. Spread a layer of rice, place chicken pieces along with the gravy. Throw in green chilies, fried onions, a boiled egg and fried potato halves. And a generous sprinkle of ghee.
Follow this with yet another layer of rice and on it, the remaining cooked chicken with the gravy, green chilies, fried onions, a boiled egg and the fried potato halves. Again a luxuriant dollop of ghee.
Finally another layer of rice. Gently pour over the saffron infused milk, keora water and the remaining ghee. Cover the lid and seal firmly with flour dough.
Place the pan on another flat frying pan and cook over low flame for 15-20 minutes.
A standing time of 10 odd minutes and the biriyani ready to serve.