1Heat oven to 350°F. Spray 60 mini muffin cups with cooking spray. In large bowl, beat cake mix, water, oil and egg whites with electric mixer on low speed 30 seconds. Beat on high speed 2 minutes. Tint batter with pink food color. Divide batter among muffin cups, filling three-fourths full. Bake 10 to 12 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes; remove from pans to cooling racks. Cool completely.
2Divide frosting into 3 bowls. Tint 1 bowl of frosting purple. Tint 1 bowl of frosting pink. Leave remaining frosting white. In large disposable decorating bag fitted with large star tip, place spoonfuls of each color frosting side by side, alternating colors and working up from tip of bag. Do not mix colors.
3To assemble, drop 1 cupcake into each push-it-up pop container. Pipe frosting on cupcake. Top each with second cupcake; pipe frosting on cupcake. Sprinkle with candy sprinkles. Frost remaining 36 cupcakes; sprinkle with candy sprinkles. Serve with push-up cakes, or freeze unfrosted for later use.