Curdle 3 cups boiling milk with lemon juice, strain whey, and rinse chenna.
In a non-stick pan, simmer remaining 1 cup milk and sugar until thickened.
Add fresh chenna and cardamom powder; cook on low flame stirring continuously for 8 minutes until mixture leaves pan sides.
Transfer into a greased tin, press level, top with sliced pistachios, and set for 2 hours.
Cut into moist squares.