Measure egg whites, adding or removing whites as needed to equal 1-1/2 cups. Place in a mixing bowl; let stand at room temperature for 30 minutes.
Meanwhile, sift confectioners' sugar and flour together three times; set aside.
Add cream of tartar, extracts and salt to egg whites; beat on high speed. Gradually add sugar, beating until sugar is dissolved and stiff peaks form.
Fold in flour mixture, 1/4 cup at a time. Gently spoon into an ungreased 10-in. tube pan. Cut through batter with a knife to remove air pockets.
Bake at 350 degrees F for 40-45 minutes or until cake springs back when lightly touched. Immediately invert pan; cool completely before removing cake from pan.
Notes
59 mg sodium, 23 g carbohydrate, 0 fiber, 3 g protein