Put a deep-bottomed non-stick pan on low to medium flame and add khoya along with powdered sugar in it. Stir continuously and cook the khoya or mawa for about 15 minutes.
Once the khoya is cooked, transfer it into a big plate and allow the mixture to cool completely. Divide the mixture into two equal portions.
Take one portion of the khoya in a deep bowl and add powdered pistachios, cardamom powder, rose essence and green food colour in it, mix well.
Now, take the other half of khoya in a large bowl and add cocoa powder in it. Mix it well too! Next, put a cling wrap on a wooden board or a flat surface and grease it using ghee.
Place the prepared pista mixture over it and spread it evenly using your hands to form a 175 mm × 200 mm (7”× 8”) rectangle. Make a cylinder roll of the chocolate mixture and place it over the pista mixture leaving (1”) side from the bottom. Roll it very tightly with the help of a cling wrap.
Gently remove the cling wrap to get a roll and cut into 15 equal slices and flatten it very lightly. Refrigerate the slices for 15 minutes. (Optional: You can garnish with chopped pistachios and silver waraq and enjoy!)