Spray 9-inch square baking pan with cooking spray. In large bowl combine dry ingredients; stir until smooth. Pour into prepared pan. Bake in 350 degree F 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 1/2 cup sauce.