Pick and wash basmati rice in plenty of water and soak in sufficient water for half an hour.
Peel and finely slice onions. Peel ginger, garlic and grind together to a fine paste. Clean, wash and finely chop fresh coriander and mint leaves.
Wash tomatoes and make a puree in a blender. Whisk the skimmed milk yogurt and keep aside. Soak the saffron in one-fourth cup warm water.
Boil three to four cups water in a thick-bottomed vessel, add bay leaf, cloves, green cardamoms, black cardamoms, cinnamon, mace and one teaspoon salt. When the water starts boiling rapidly, drain the soaked basmati rice and add.
Cook for eight to ten minutes, stirring frequently or until the rice is three fourth done. Drain in a colander.
Heat oil in a non-stick pan, add sliced onions and stir-fry over high heat for two to three minutes or until the onion turns translucent. Add ginger-garlic paste and cook briefly.
Add red chilli powder, coriander powder, crushed peppercorn, cumin powder and turmeric powder. Stir-fry briefly and add the pureed tomatoes.
Continue cooking over high heat for another two to three minutes, stirring continuously or until masala is fairly thick.
Add the whisked skimmed milk yogurt, garam masala powder and half the quantity of chopped fresh coriander and mint leaves. Stir well and cook for two minutes more.
Add the paneer and salt to taste. Stir-fry over high heat for two to three minutes and remove from heat.
Arrange the cooked rice and paneer masala in alternate layers in an oven proof dish (or biryani handi), sprinkling the chopped fresh coriander and mint leaves, kewra water and the water with saffron after each layer. Ensure that the top most layer is of rice.
Cover the assembled biryani with a tight-fitting lid and seal the edges with kneaded atta dough (if required).
Keep the sealed dish on a tawa and cook on low heat for ten to fifteen minutes. You can also place a few burning charcoals on the lid. Alternately, cook in a pre-heated oven at moderate temperature for ten to fifteen minutes.
Break open the seal and serve biryani immediately.