1. Soak pistachio nuts in boiling water for 35 minutes.
2. Grease and base-line an 7 " square plate.
3. Drain pistachio nuts thoroughly and grind with milk until finely chopped.
4. Stir in sugar.
5. Heat a large frying pan, add butter or ghee and melt over a low to medium heat.
6. Add nut paste and cook for about 15-20 minutes, stirring constantly, until mixture is very thick.
7. Stir in vanilla essence, then spread into prepared greased plate.
8. Leave to cool completely, then cut into Square or diamond shape pieces.