1Heat oven to 350°F (325°F for dark or nonstick pans). Grease with shortening or cooking spray bottom only of 2 (6-inch) round cake pans and place paper baking cups in 6 regular-size muffin cups.
2In large bowl, beat cake mix, bananas, oil, water and eggs with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes, scraping bowl occasionally until smooth. Place 1 3/4 cups batter into each round cake pan. Spoon remaining batter into 6 lined muffin cups. Bake round cake 35 to 40 minutes and cupcakes 18 to 23 minutes or until toothpick inserted in cake comes out clean. Cool 10 minutes; remove from pans to cooling rack. Cool completely, about 30 minutes.
3To frost and decorate cake, slice 6-inch cake tops horizontally to remove rounded tops. Place one round cake cut side up on plate. Spread cut side with frosting. Top with remaining round cake cut side down. Frost top and sides of cake with frosting. Arrange cereal in single layer over top and sides of cake. Place candle in top center of cake. Use remaining frosting to frost cupcakes. Decorate with cereal, if desired.