Spray 23 cm square baking pan with cooking spray. In large bowl combine dry ingredients; stir until smooth. Pour into prepared pan. Bake in 180ºC oven 35 minutes or until toothpick inserted in center comes out clean. Cool in pan on wire rack. If desired, serve with Fat-Free Yogurt Cream Sauce. Each serving (without sauce) provides: 0 g total fat, 0 mg cholesterol, 130 Calories, 3 g protein, 29 g carbohydrate, 150 mg sodium FAT-FREE YOGURT CREAM SAUCE: Line a strainer with paper coffee filter or cheesecloth layers. Add yogurt, set over bowl and refrigerate 4 hours. Discard drained liquid. Combine thickened yogurt and sifted confectioners' sugar; stir until smooth. Makes about half cup sauce.