Grease small bowls or a dish with butter and then sprinkle sugar on the side.Mix sugar and the cocoa with milk bring it to a boil.Add the cornflour paste stirring continuously.Mix the butter, remove from fire cool and add essence.Add beaten egg yolk one at a time keep aside till serving time.Half an hour before serving beat the egg whites till stiff.Fold the stiff egg whites into the chocolate mixture.Pour the mixture into the prepared bowls and bake for 30 mins at 180 degrees. Serve immediately
