Wash Basmati rice and soak in water for 15 mins.
Chop Onions into fine pieces, slit green chillies in middle.
Heat butter in the cooker that's going to be used for cooking Rice, add all whole spices. then add onions, ginger garlic paste, green chillies. Sim the flame.
Wash and chop coconut and run in a mixie to get its milk. Extracted coconut milk can be stored for 2 - 3 days. But thick paste can stay for a week in fridge. It should not be handled by hand, rather use spoon, this way it stays longer.
Once the Onions turn golden brown, add drained rice. Sauté for a while until it is coated well. Add coconut milk, water, salt. and put it for 2 whistles. The rice should not be over cooked but the grains should be separate.
Finally garnish with coriander leaves.