1 c. sifted cake flour
1/3 c. unsweetened cocoa
1 tsp. each baking soda and baking powder
6 lg. egg whites
1 1/3 c. firmly packed brown sugar
1 c. unflavored nonfat yogurt
1 tsp. vanilla
Powdered sugar

Mix flour, cocoa, baking soda, and baking powder. In a large bowl beat whites, brown sugar, yogurt, and vanilla until well blended. Stir in flour mixture and beat until evenly moistened.

Pour batter into a nonstick 8 inch square pan (or coat an unfinished pan lightly with cooking oil spray or salad oil, and dust with flour). Bake in a 350 degree oven until cake springs back when lightly pressed in center, 30 to 40 minutes. Let the cake cool for 15 minutes, then invert it onto a serving plate.

Sift powdered sugar over cake (if desired, use a doily as stencil for sugar pattern). Serve warm or cool. If made ahead, wrap airtight and store in a cool place up to 2 days. Cut into squares. Makes 8 servings.