Melt the butter and mix in the biscuit crumbs and then press into a dish.
For the Filling: 3 x 12oz packets of Philadelphia cream cheese, 1 tin of condensed milk, the juice of three lemons (just typing this is making my mouth water).
Beat the condensed milk with the cream cheese, then add the lemon juice and spread onto the base. Pop in the fridge until you are ready to scoff. Then decorate with grated dark chocolate. You will never look back.