After 10 minutes of rest time, combine ghee in a heavy-bottomed pan.
Reduce the flame to a medium setting, and add sifted besan to the Kadai.
Using a spatula or perforated spoon, start roasting the besan. Keep stirring continuously and roast the besan for 7-9 minutes. The besan mixture will become runny and all bubbly. Stir continuously over medium heat.
Another 4-6 minutes into the cooking, besan will start to change color and become caramel-y. The total roasting time for me was 14-15 minutes.
Turn the heat down and add milk powder and stir until it is well absorbed in the besan mix.
Turn off the heat and allow the besan to cool slightly. But keep stirring as the Kadai is still hot.
Once the besan has cooled comfortably ( at room temperature), add the sugar syrup.
Turn the heat to a medium-low setting and mix until the sugar syrup is completely absorbed in the besan. Be extra careful, as the mixture will start to bubble as the water evaporates.
Keep stirring for another 2-3 minutes until it forms a thick mass.
Add slivered pistachios and mix.
Grease an 8×8 pan with ghee. Line it with parchment paper and grease the parchment paper too with ghee. Transfer the Mohanthal to this prepared pan and spread it around the pan in a single layer.
Garnish with some more slivered pistachios and let it rest for 5-6 hours or overnight.
Once set, divide Mohanthal into equal pieces and serve.