Coat insides of 2 large microwave-safe mugs with oil or butter.
Place cranberries and 1 tablespoon champagne in small bowl. Microwave on HIGH 10 seconds; drain. Divide cranberries and place in bottom of mugs.
Whisk together whipped cream, egg whites and cake mix in medium bowl. Place half of batter in each mug.
Microwave each mug individually on HIGH 1 minute 15 seconds to 1 minutes 30 seconds or until set. Invert each cake onto a plate. Spoon 1 ½ tablespoons champagne over top of each cake. Serve with additional whipped cream, if desired.