If your mawa is frozen, thaw it completely before using.Grate the mawa using a box grater. Once its soft, you can crumble it using hands too.
Add unsalted, shelled pistachios to your food chopper and pulse to grind into a powder. Avoid running the processor for too long at once else the nut oils will start releasing and instead of powder, the pistachios will become pasty.
Add the mawa to a nonstick pan and place it on the stove over low heat. Stir continuously with a spatula as the mawa softens. This happens quickly, and you don't want it to burn. Takes around 2-3 minutes. If your mawa feels dry, add about 1-2 tablespoon of milk or as needed, gradually.
Once the mawa has softened (don't let brown, add the sugar and pistachios. Mix well until everything is combined.
Cook the mixture on low heat for 7-10 minutes. It will feel thinner and viscous as pistachios warm up and sugar melts at first. Cook until the mixture starts leaving the sides of pan, starts feeling heavy and clumping around the spatula. It will leave sides of the pan. Once ready, the mixture will not spread (or spread very slowly) and stay in one place on the pan. Don't dry out.
Turn off the heat and sprinkle the cardamom powder and add 1-2 drops of rose essence. Combine well and transfer to a plate. Let the ladoo mixture cool down for 6-10 minutes or until okay to touch.These ladoo are quite rich.
Grease your hands lightly with ghee(if needed), scoop the mixture using a cookie scoop(best tool!) or divide into 12-14 portions, and roll between palms them into smooth ladoos. Stick chopped pistachios on top.Store refrigerated for 3-5 days. You can freeze them too.
Notes
Powdered sugar has cornstarch in it which helps with the texture of the ladoo.
The sugar quantity can go up 1-2 tablespoons if you like sweeter ladoos.Adjust cooking time to reach the desired consistency.