Grind biscuits in your processor. In a bowl, mix ground biscuits with butter. Rub with fingertips till butter melts and you get a crumbly mix.
Grease a 8" loose base cake tin and evenly spread the biscuits. Refrigerate for at least 30 minutes.
Grate zest out of lemons (do not discard). Boil milk and curdle it with juice of two lemons. Strain and keep the chhena in a muslin cloth or a sieve and let it cool. DO NOT WASH, THE LEMON FLAVOUR IS CRUCIAL
Churn chhena with about 2-4tbsp of yogurt to get a smooth yet thick cream cheese mixture.
Beat this cream cheese with powdered sugar till smooth. Add one egg at a time and beat just enough to incorporate the it. DO NOT OVERMIX, IF THE MIXTURE GETS TOO AIRY, THE CHEESECAKE WILL CRACK. Cut and fold in 2 tbsp of flour.
Gradually add cream and essence and gently whip. Add lemon zest and yogurt. Whip softly and finally add remaining lemon juice. Fold in another 2 tbsp of flour. After one last gentle whip, pour this over the biscuit mix and bake in a preheated oven at 170 degree celsius for 60mins.
Leave the cake in the oven for an hour after baking, don't rush to get it out. Don't open the oven frequently while it bakes. it will crack the cake.
Once the cake it cooled, you can top it with 1/2 cup of fresh cream mixed with a tablespoon of yogurt, 2 tsp of lemon juice and 1 tbsp icing sugar.