WHITE BATTER:

1 3/4 c. egg whites (12-14), room temperature
1 1/4 c. sifted cake flour
1 1/2 c. sugar
1/2 tsp. salt
1 1/2 tsp. cream of tartar
1 1/2 tsp. vanilla extract

YELLOW BATTER:

5 egg yolks
2 tbsp. cake flour
2 tbsp. sugar
2 tbsp. grated lemon peel
Confectioners sugar

Make white batter: Sift 1 1/4 cups flour with 1/2 cup sugar together. In large bowl mix at high speed: egg whites with salt and cream of tartar until soft peaks form when beaters are raised. Beat in 1 cup sugar, 1/4 cup at a time; beat well until stiff peaks form when beater is slowly raised.

With wire whisk fold vanilla into egg whites. Sift flour mixture, one-fourth at a time, over egg whites. With wire whisk, use under and over motion and fold in each addition with 15 strokes, rotating bowl. Turn 1/3 of batter into a medium bowl. Preheat oven to 375 degrees.

Make yellow batter: In small bowl combine yolks, cake flour and sugar with mixer at high speed until very thick. Add lemon peel. With wire whisk, fold yolk mixture into reserved 1/3 batter.

To marble, spoon batters alternating into an ungreased 10-inch tube pan, ending with white batter on top. With knife, cut through batter twice and gently spread batter evenly on top.