Sift Presto with sugar. Stir butter to soften. Add flour mixture and milk. Mix until all flour is moistened. Then beat 2 minutes at medium speed of electric mixer. Add egg whites and flavoring; beat 1 minute longer with mixer.
Baking: Pour batter into 2 greased and floured 8-inch layer pans. Bake at 350° for about 30 minutes or until cake tester comes out clean. Cool cakes in pans for 10 minutes. Remove from pans and finish cooling on racks.
Alternate Baking Pans: One 13x9 inch pan for approximately 30 minutes.
Two 9-inch layer pans for approximately 25 minutes.