Rinse potatoes well under running water scraping any mud sticking to their skin. Cook them in pressure cooker or steamer till soft.
Peel them off and mash well such that there are no lumps left. Measure this mashed potato and keep aside. Heat ghee in a pan and let it melt.
Include mashed potato to the ghee and keep stirring. The potato will absorb all the ghee at this stage.
Continue stirring in medium flame for few minutes till the color changes.
As the color changes to light brown, include sugar and continue stirring till all the oozes out and doesn't stick to the pan anymore.
Sprinkle cardamom powder and garnish with chopped pistachio. Drooling potato halwa is ready to relish.
Notes
While cooking mashed potato do not leave the pan unattended. It may burn the bottom and can ruin the taste.
I have used up 2 cups of mashed potato to make this halwa and added 1/2 cup of sugar to it. The sweetness was just right for me. You can even raise sugar to 3/4 cup.
This halwa tastes very good when fresh. After storing for a day, the halwa thickens.
You can even add food color of your choice to make it more attractive. I haven't added any food color.