1/3 c. cake flour
1/3 c. unsweetened cocoa powder
2 Tbsp. cornstarch
1/2 t. baking soda
1/2 t. baking powder
1/3 t. salt
4 lg. eggs, separated
1 c. sugar, divided
Confectioners sugar
Filling:
8 oz. cool whip, thawed

Cake:
Preheat oven to 350 degrees. Line a 15-by-10-inch jelly roll pan with waxed paper. Grease and flour the lined pan.
In a medium bowl combine flour, cocoa, cornstarch, baking soda, baking powder, and salt. Mix well.
In a separate bowl, using an electric mixer, beat egg yolks and 1/4 c. sugar on medium speed until fluffy.
In a small bowl, using clean beaters, beat egg whites on high until foamy. Gradually add 1/2 c. sugar, beating until stiff, but fluffy, and peaks form.
Fold 1/3 beaten egg whites into egg yolk mixture. Alternately fold in remaining whites and flour mixture. Pour batter into pan.