Preheat oven to 350. Prepare 24 standard muffin cups with cooking spray and flour; set aside To prepare batter, combine cake mix, whipped topping mix, and baking powder in a mixing bowl. In another mixing bowl, combine water, egg whites, oil, and vanilla extract. Mix dry ingredients with wet ingredients just until moistened. Spread batter evenly between muffin cups. Bake 20 minutes or until top springs back when touched. Cool. Prepare frosting mix according to package directions. Spread over cooled cupcakes. Top each cupcake with Peep and jelly beans.