Add the ricotta cheese, sugar, and mango pulp to the pot and mix well.
Secure the lid, close the pressure valve, and cook for 10 minutes at high pressure. (This is a good time to grind cardamom if you don’t have some on hand).
Quick-release pressure.
Press saute and adjust the heat to the highest setting. Add ghee, milk powder, and cardamom to the pot and stir continuously for 5 minutes (you may want to wear a glove to hold onto the hot pot as you stir). If the mixture still looks a bit liquidy, you can stir for another minute or so if needed.
Pour the mixture into a parchment-lined 8×8 pan and even out the top with a spatula if needed. Sprinkle chopped pistachios on top, then gently shake the pan to help level the fudge and help the pistachios stick.
Let the milk cake cool down (takes about an hour), then put it in the fridge for 4 hours to set. You can also leave it overnight.
Once chilled, lift from the pan using parchment, then cut into 5 rows by 5 rows (approx. 1.5-inch x 1.5-inch squares). Trim off any uneven edges.
You can store this mithai in an air-tight container in the fridge for about a week.