Preheat the oven to 350 degrees F. Lightly coat the bottom of a 9 by-13-inch cake pan with cooking spray.
In a large mixing bowl combine the cake mix, Champagne, vegetable oil, and egg whites. Beat on low speed with an electric mixer until just combined. Scrape down the sides of the bowl with a rubber spatula and continue beating on medium speed for 2 minutes. Pour into the prepared cake pan and bake for 30 to 35 minutes, or until a toothpick inserted into the cake comes out clean. Remove it from the oven and cool completely.
Empty the frosting into a small bowl and add the Champagne flavoring. Stir to combine and set aside.
To make the mini-cakes, with a 3-inch ring mold (or use an 8-ounce pineapple can with top and bottom removed) stamp out 6 cakes. Slice the cakes in half, horizontally, to make layers. Frost the bottom layer, replace the top layer and frost the tops and sides of cake. Decorate with the disco balls, Dragees, and glitter, if using.
Cook's notes: Champagne flavoring and edible glitter are available where cake and candy making supplies are sold. Dragees, or silver candy balls, are not available in all states.