Preheat oven to 350 degrees F. Spray 60 mini muffin cups. Make cake batter as directed on box. Divide batter among 5 small bowls, about 3/4 cup each. Make 5 different colors of batter by adding 1/4 teaspoon gel food color to each bowl; blend well. Fill each muffin cup with 1 level measuring tablespoon batter, making 12 cupcakes of each color. Bake 10 to 12 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes; remove from pan. Cool completely, about 10 minutes. In large bowl, beat marshmallow creme and butter with electric mixer on medium speed until blended. Beat in powdered sugar until fluffy. Divide frosting among 5 small bowls, about 1/3 cup each. Using the same 5 gel food colors, lightly tint frosting in each bowl to match the cupcake colors. Assemble each popper using 2 mini cupcakes. Cut tops off each cupcake horizontally (save bottoms for another use). Spread or pipe about 1 tablespoon frosting on cut side of 1 cupcake top. Form a sandwich by placing cut side of second cupcake top on filling; press lightly. Repeat with remaining cupcake tops. Store loosely covered.