Take a pan and heat ghee into it. Put mawa into the pan and roast it on a medium flame till it turns light pink in colour. Now take it out in a bowl and let it cool down.
Take a tray or a plate and grease it with little oil.
Put sugar in a pan with water of 1/3 quantity of sugar to make syrup (chashni) (take 80 gms water for 250 gms sugar). Make a thick syrup, enough thick that it sets as soon as it is dropped on a plate. Test the consistency of the sugar by taking a drop between your fore finger and thumb. If it is too sticky and sets quickly between your fingers, then your syrup is ready. Now turn off the flame.
Cool down the syrup by stirring it continuously with the spoon. As soon as it cools down and starts to set, put mawa into it and mix it well with the syrup. Add cardamom powder also to the mixture.
Pour the mixture in the greased tray and spread it evenly into it. Garnish the mixture with chopped almonds and pistachios.
It takes 20-24 hours for a barfi to set and freeze. Once the barfi sets, cut it into the desired shape and size.
Your delicious Mawa Barfi is ready. Store it in an air-tight container in the refrigerator and eat whenever you like.