Prepare and bake your cupcakes according to the mix’s directions. Most cake mixes yield two dozen cupcakes.
Cool your cupcakes on a wire rack before decorating.
To begin the decorating process, make your buttercream. In a large bowl and using an electric mixer, beat together your butter, confectioners’ sugar and milk. Start on low and gradually increase to high.
Once the buttercream is smooth, scoop into a frosting bag and pipe out a dollop of icing on each cupcake.
Roll out each fondant color so that it’s about ¼ of an inch thick. Using your cookie cutters, cut out 48 X’s of each color and 48 O’s of each color.
Place the fondant shapes on each cupcake, alternating colors. Serve and enjoy!