1 3/4 cups egg whites (12 to 14)
1 1/2 teaspoons cream of tartar
1 1/2 teaspoons vanilla extract
1 1/4 cups sifted cake flour (sift before measuring)
1 1/2 cups sugar
1/2 teaspoon salt
5 egg yolks
2 tablespoons cake flour
2 tablespoons sugar
2 tablespoons grated lemon peel
Preheat oven to 350 degrees. Beat egg whites, adding cream of tartar 1/2 teaspoon at a time. Add vanilla. Combine 1 1/4 cups flour, 1 1/2 cups sugar and salt; fold into egg whites. Place in 9 by 13 inch pan. Prepare yellow batter by adding 2 tablespoons flour, 2 tablespoons sugar and lemon peel to beaten egg yolks. Pour yellow batter on top of white batter. Using a knife, cut through batter to give a yellow-white swirled effect. Bake for 35 to 40 minutes.
To get good volume, let egg whites warm to room temperature before beating. Be sure to use cake (not all-purpose) flour in this recipe. If you are baking the cake a day ahead, leave it in the pan overnight and remove it just before serving. Cut cake with a knife that has a serrated edge, using a light sawing motion.
Makes 12 servings.