Preheat oven to 375º. Sift Swans Down® Cake Flour, then lightly spoon into measuring cup for 1 ¼ cups. Add ½ cup sugar, and sift four times. In a separate, very large bowl, combine egg whites, cream of tartar, salt, and flavorings. Beat at high speed of electric mixer until moist soft peaks form. Add balance of sugar in 4 additions, beating until blended after each addition. Sift in flour mixture in 4 additions, folding in with large spoon; turn bowl often. Bake: Pour into ungreased 10-inch tube pan. Bake at 375º, 35 to 40 minutes. Cool cake upside down in its pan, on a cake rack (or placed on an upside-down funnel or heatproof bottle) for about 1 hour or until comfortable for handling.
Use only metal or glass mixing bowls when making Angel Food Cake. Plastic or ceramic bowls retain oils which will disturb the rising process.
When beating egg whites try not to under beat or over beat; egg whites should be stiff but not dry. To prevent air pockets, after filling your angel food cake pan with batter simply use your spatula to press batter into sides and bottom of pan. Or you can cut through batter with a knife to remove air bubbles.