In a heavy-bottomed pan, pour 1 litre of full-fat milk and bring it to a boil. Keep stirring occasionally to prevent it from sticking to the bottom.
Once the milk starts boiling, reduce the heat to low and let it simmer for 30-40 minutes, stirring occasionally, until it reduces to half its original volume.
Add 100 grams of sugar to the reduced milk and stir well until the sugar dissolves. Cook for another 5 minutes.
In a separate bowl, mash 200 grams of fresh blackberries to form a puree. You can also use a blender for a smoother texture.
Add the blackberry puree to the milk mixture and mix well. Cook for another 5 minutes, stirring continuously.
Remove the pan from heat and let the mixture cool down to room temperature.
Once cooled, pour the mixture into kulfi moulds or small cups. Cover with aluminium foil or plastic wrap and insert a wooden stick or ice cream stick in the center of each mould.
Freeze the moulds for at least 6-8 hours or overnight until the kulfi is completely set.
To serve, gently remove the kulfi from the moulds by running them under warm water for a few seconds. Enjoy the delicious blackberry kulfi!