Peel the lauki and cut it into ling chunks, remove the soft centre part that has seeds and discard them.
Heat a pan and add desi ghee.
Quickly thickly grate the lauki and immediately put in a pan to start cooking on slow heat. Cook for 5 mins.
Add milk and cardamom powder and bring to a boil. On low heat cook for 10mins. Add sugar and cook again. Once it has reduced sufficiently add grated khoya and stir for 5 mins or till the halwa thickens up. Add chopped nuts. Remove and serve hot.