1Preheat oven to 350 degrees F (175 degrees C). Sift cake flour and confectioners sugar together 5 times and set aside.
2In a large clean bowl, whip egg whites with a pinch of salt until foamy. Add cream of tartar and continue beating until soft peaks form. Gradually add sugar while beating, and continue to beat until very stiff. Add vanilla.
3Quickly fold in flour mixture. Pour into a 10 inch tube pan.
4Bake at 350 degrees F (175 degrees C) for 45 minutes.