Powdered Sugar Angel Food Cake
["12 egg whites (room temperature)", "1 1/3 tsp. cream of tartar", "2/3 c. sugar (granulated)", "1 1/2 c. powdered sugar", "1/2 tsp. salt", "2 tsp. vanilla"]
["Beat egg whites and cream of tartar until stiff.", "Fold in 1 tablespoon at a time the granulated sugar.", "Sift together the powdered sugar, flour and salt.", "Fold into egg mixture.", "Add vanilla.", "Bake in tube pan at 375\u00b0 for 45 minutes.", "Invert the cake while cooling."]
["egg whites", "cream of tartar", "sugar", "powdered sugar", "salt", "vanilla"]