Wash the sweet potatoes thoroughly to remove dirt. Cut them into medium-sized pieces. Steam the sweet potatoes... Steam for about 15–25 minutes, depending on the size of the pieces, until they are soft and fully cooked.

Allow the sweet potatoes to cool slightly. Remove the skin and cut the flesh into smaller pieces. Put the cooked sweet potato pieces into a mixer or blender add milk. Blend until smooth. Avoid adding extra water unless necessary.

Heat oil or ghee in a heavy kadai (wok) or pan. First fry the cashews.
Remove when they become golden and keep aside. In the same ghee add the mashed sweet potatoes.. Stir well and sauté for 3 to 4 mins on medium-low to medium heat.

Add brown sugar. Mix and sauté for 4 to 5 mins on medium-low to medium heat.

Keep on stirring and cooking the halwa till the oil or ghee starts to leave the sides of halwa. This will take approx. 10 to 12 minutes on a medium-low to medium heat.
Lastly add the fried cashew nuts, cardamom powder and stir again.

Serve sweet potato halwa hot, warm or cold.