cooking spray  | 
                                                1 tablespoon all-purpose flour  | 
                                                1/2 cup reduced-calorie stick margarine, softened  | 
                                                1 1/4 cups firmly packed brown sugar  | 
                                                1 teaspoon vanilla extract  | 
                                                3 large egg whites  | 
                                                1 large egg  | 
                                                1 1/2 cups all-purpose flour  | 
                                                1/2 teaspoon baking powder  | 
                                                1/4 cup unsweetened cocoa  | 
                                                1/4 cup reduced-fat creamy peanut butter  |