Add the grated carrots and milk to a heavy pot. Bring to a boil, then reduce to medium-low.

Cook for 50 to 60 minutes in a wide, heavy pan, stirring often, until nearly all the milk has been absorbed.

Add the sugar and stir. The mixture will loosen; cook for 5 to 8 minutes until it thickens again.

Add the ghee and cardamom and cook for 8 to 10 minutes, stirring, until the halwa leaves the sides of the pot and looks glossy.

Stir in half the nuts and the raisins. Serve warm, topped with the remaining nuts.