1Heat oven to 350°F (325°F for dark or nonstick pans). Spray bottoms and sides of two 8- or 9-inch round cake pans with baking spray with flour.
2In large bowl, stir together cake mix and 1 1/4 cups champagne. Add oil, egg whites and food color; beat with electric mixer on medium speed 2 minutes. Pour into pans.
3Bake as directed on box for 8- or 9-inch rounds. Cool 10 minutes. Remove cakes from pans to cooling racks. Cool completely, about 1 hour.
4In medium bowl, beat frosting ingredients with electric mixer on medium speed until smooth. On serving plate, place 1 cake layer, rounded side down. Frost top of cake layer. Top with second layer, rounded side up. Frost side and top of cake. Sprinkle with garnishes. Store loosely covered.