Firstly rinse, peel and grate 300 grams lauki. Before grating taste the lauki. If it tastes sour or bitter then discard and do not cook it. 

Heat 4 tablespoons ghee in a heavy pan or kadai on medium-low to medium flame. Use a large kadai so that milk does not splutter outside.

Add the grated lauki. Mix grated lauki very well with the ghee. On a low to medium-low flame begin to saute the lauki. Stir often when sauteing lauki.

Saute lauki till the moisture dries. Then add 2 cups full-fat milk. mix very well. Continue to cook on a low to medium-low flame till the milk comes to a boil. In between do stir at times.

The milk will start boiling. At this step be attentive and keep on stirring, so that the milk does not spill from the pan. Stirring often continue to cook till ¾ or 75% of the milk has reduced and absorbed.

Add sugar and chopped nuts. Mix very well. Stirring often cook till the halwa mixture starts coming together and thickens.

Then switch off the flame 
Garnish with some chopped nuts and serve lauki halwa hot or warm.