Preheat oven to 275-300 degrees. Grase a 6x10 inch pan.

Cream butter, sugar and vanilla. Add egg yolks. Add flour, baking powder, salt, dates, and nuts. Add beaten egg whites. Pour into pan and bake 45 minutes.

(The author of this recipe forgot to say when to add the vanilla, so I put it in where I thought it ought to go.)