If you want you can pressure cook the mutton separately with salt, turmeric powder and 1 tsp Chilli powder for 2 whistles.
Else if you are using the same pan for the entire cooking, then first heat oil, roast the onions till brown, remove.
then add the mutton with salt turmeric powder and 1 tsp chilli powder, 1 cup water and bring to boil, simmer for 10 mins. Drain the water and pieces. Save the water for later use.
In the same wide pan, add the ghee, oil, after couple of minutes, add all the whole spices. Saute well.
Then add ground paste, saute for couple of minutes on high.
Now add the finely chopped mint and coriander leaves. Cook on high.
After few minutes, add the drained mutton pieces, combine well.
Add the red chili powder, coriander powder, salt and let it cook for about 5 to 7 mins, till oil comes out on the sides.
Now add the curds, and continue cooking on high for the entire ingredients to get mixed well and cooked.
Add the browned onions and combine well.
Measure the cooked broth and add remaining water. The ratio is 1:2, however on the whole you can reduce 1/2 cup water finally. Measure the liquid to 6.5 cups.
Bring to a boil, add the drain rice and stir well.
Cover with lid and cook on high till the water is all evaporated. Then simmer and keep over another pan for dum cooking for about 15 to 20 mins.
Continue cooking till the liquid evaporates and the rice is cooked almost. Simmer, add the saffron along with milk. Cover with lid and cook for another 10 mins on very low flame.