Preheat oven to 150 degrees C. Grease and flour a 25cm ring tin.
In a large bowl combine dates, walnuts, sugar, baking powder and flour. Stir in egg yolks. In a large glass or metal mixing bowl beat egg whites until stiff peaks form. Fold the whites into the fruit/nut mixture until no streaks remain. Spoon into prepared tin.
Bake in the preheated oven for 90 minutes. Let cool in pan for 10 minutes then turn out onto a wire rack and cool completely.