Preheat oven to 350° F.
Grease and flour 1 (9 inch) cake pan.
Beat flour, sugar, baking powder, salt, shortening, milk and vanilla on medium speed, scraping occasionally for 2 minutes.
Add egg whites and beat on high speed, scraping bowl occasionally 2 minutes.
Pour into pan and bake until pick comes out clean about 35 minutes.
Cool 10 minutes on rack turn out with second rack