Preheat oven to 325°F. For the Cupcakes, beat egg whites in medium bowl with electric mixer on high speed until soft peaks form. Beat remaining ingredients in large bowl with electric mixer on low speed to moisten. Beat on medium speed 2 minutes. Gently stir in egg whites until combined. Spoon into 18 paper-lined muffin cups, filling each 3/4 full.
Bake 18 to 20 minutes or until toothpick inserted into cupcake comes out clean. Cool in pans on wire rack 5 minutes. Remove from pans; cool completely.
For the Frosting, beat all ingredients in large bowl with electric mixer on low speed 3 minutes. Scrape sides and bottom of bowl with spatula. Beat on high speed 3 to 5 minutes or until light and fluffy. Frost cooled cupcakes with Frosting. Serve immediately.