Add the sugar and water to the pot and mix well.
Secure the lid, close the pressure valve, and cook for 11 minutes at high pressure.
Add ghee, milk powder, and cardamom to the pot and quickly mix (using either a spoon or a whisk) until well combined. You may want to wear a glove to hold onto the hot pot as you stir - you will need to be fast!
Pour the mixture into a parchment-lined 8×8 pan/dish (you'll need a spoon to scoop the mixture out of the pot and into the pan). Shake the pan gently so that the mixture spreads evenly. Sprinkle the chopped green pistachios on top and gently shake the pan again to help them stick.
Let the milk burfi cool down (on a wire rack - takes about 30 to 40 minutes), then put it in the fridge for 1 hour to set.
Remove the chilled fudge, slice it into medium-sized squares, and then place the individual pieces on a plate. If you eat the mithai at this point, it will be chewy. Let the fudge sit out at room temperature for 24 hours to dry out. This will completely change the texture of the burfi - make sure to give it time to dry out!
After it’s dry, you can store it in an air-tight container in the fridge for about a week. I prefer to eat this mithai at room temperature.