For the filling
2eggs, separated
7oz tin sweet condensed milk
4tbs lemon juice
3tbs caster sugar.

Melt the chocolate in a bowl over a pan of hot water. Stir in the butter. Lightly crush the cornflakes and stir in the sugar and melted chocolate.
Make the filling: whisk the egg yolks until thick & creamy,add the condensed milk and lemon juice and stir until the mixture thickens.

Whisk the egg whites until stiff but not dry. Add the sugar and continue to whisk until smooth and glossy. Fold gently into lemon mixture. Place two thirds of the chocolate mixture in the base of a freezer tray, pour the lemon filling over and sprinkle with the remaining chocolate mixture. Freeze until firm. Cut the dessert into bars to serve. Serves about 8 people.