Take 1 litre of full-fat milk in a heavy-bottomed pan and bring it to a boil. Keep stirring occasionally to avoid burning at the bottom.
Once the milk starts boiling, reduce the heat to low and let it simmer for about 30-40 minutes, stirring occasionally, until it reduces to half its original quantity.
Add 100 grams of sugar to the reduced milk and mix well. Cook for another 5-7 minutes until the sugar dissolves completely.
In a small bowl, mix 2 tablespoons of cornflour with 2 tablespoons of milk to make a smooth paste. Add this paste to the boiling milk mixture and stir continuously to avoid lumps. Cook for another 5 minutes until the mixture thickens.
Remove the pan from heat and let the mixture cool down to room temperature.
Crush 100 grams of unsalted pistachios into small pieces and add them to the cooled milk mixture. Mix well.
Pour the pista kulfi mixture into kulfi moulds or small cups. Cover with aluminium foil or plastic wrap and insert ice cream sticks in the center of each mould.
Freeze the pista kulfi for at least 6-8 hours or overnight until it sets completely.
To serve, gently remove the pista kulfi from the moulds by running them under warm water for a few seconds. Enjoy the delicious pista kulfi!