Peel the outside skin of dudhi and discard. Make thin slices using a peeler or a mandolin slicer, about 2 to 4 cups.
Set Instant Pot to Saute mode and heat ghee. Add dudhi and sauté for a minute.
Add sugar, cardamom, low fat milk and saffron. Give a quick stir. Close the Instant Pot with pressure release handle to sealing. Pressure cook for 5 minutes followed by 10 minute natural pressure release.
Open the Instant Pot. Add whole milk (or low fat) and cook on sauté (normal) mode for 15 to 20 minutes or until the basundi is of desired consistency.
Enjoy warm or chilled topped with sliced pistachios.
Notes: You can add up to ½ cup of sugar for sweeter basundi.