Heat oven to 350°F. Place paper baking cup in each of 24 regular-size muffin cups.
In large bowl, beat cake mix, water, oil, egg whites and peppermint extract with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes, scraping bowl occasionally. Divide batter in half. To 1 portion, add food color; stir until uniform in color. In each muffin cup, place 2 tablespoons red batter; top with 2 tablespoons white batter. Swirl white batter through red batter with knife for marbled design.
Bake 18 to 20 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pans to cooling racks. Cool completely, about 30 minutes.
Frost cupcakes with frosting. Top each with crushed peppermint candies.