Place the tennis biscuits into a ziplock bag. With a rolling pin, crush the biscuits until you have fine crumbs.
Mix the crushed biscuits and melted butter together and press firmly into the bottom of a greased 23 cm tart tin. Refrigerate while you make the filling.
Filling: Beat the Cremora and yoghurt together until smooth. Add the condensed milk and lemon juice and beat until thick.
Pour over the tart base and refrigerate for 4 – 5 hours or until firm.
