6 oz Chocolate, semisweet
4    Egg whites
2/3 c  Sugar
1 ts Baking powder
1    Icing sugar
1/2 c  Hot water
1 ts Vanilla
2/3 c  Flour, all-purpose
1 pn Salt

In large heatproof bowl set over hot water, melt chocolate with water,
stirring until smooth. Remove from heat; let cool slightly.
Whisk in egg whites and vanilla. Stir together sugar, flour, baking powder
and salt; stir into chocolate batter just until combined. Pour into
lightly greased 8 in. square cake pan. Bake in 350F oven for 20 to 25
minutes or until edges pull away from pan. Let cool on rack; dust with
icing sugar.
Per serving: about 110 calories, 2 g protein, 4 g fat, 19 g carbohydrate.