1 c. sifted cake flour
1/3 c. unsweetened cocoa
1 tsp. baking powder
1 tsp. baking soda
6 lg. egg whites
1 1/3 c. firmly packed brown sugar
1 c. unflavored (plain) non-fat yogurt

Mix flour, cocoa, baking soda and powder. In large bowl beat egg whites, brown sugar, yogurt and vanilla until well blended. Stir in flour mixture and beat well. Pour batter in greased 8 inch pan. Bake at 350 degrees for 30-40 minutes. Sift powdered sugar on cooled cake.