Angel Food Cake

I made this for my mom's birthday. I'm usually too lazy to make cakes from scratch, but she asked for this recipe and since I love her....of course I made it. =) Credit to Southern Living.

12 egg whites
1 1/2 tsp. cream of tartar
1/4 tsp. salt
1 1/2 c. sugar
1 c. sifted cake flour
1 1/2 tsp. vanilla extract

Beat egg whites (at room temp.) until foamy. Add cream of tartar and salt; beat until soft peaks form. Add sugar, 2 tbsp. at a time, beating until stiff peaks form. Sprinkle flour over egg white mixture, 1/4 c. at a time; fold in carefully. Fold in vanilla.
Pour batter into an ungreased 10-inch tube pan, spreading evenly. Bake at 375 F for 30-35 min. or until cake springs back when lightly touched. Invert pan; cool 40 min. Loosen cake from sides of pan using a narrow metal spatula; remove from pan.

*for Chocolate Angel Food Cake, sift 1/4 c. cocoa with flour.