You will need all 24 cupcakes to make the football shape. Arrange your cupcakes on the rectangle board by lining them up one line at a time. Start in the middle to make 3 vertical lines next to each other of 4 cupcakes each. Then work your way out to the end of each side with one line of 3 cupcakes, then one line of 2 cupcakes, then one cupcake to finish (on each side).
Now that you have your template, you will lift each cupcake and spread a little dollop of frosting on the bottom then stick it back into the football shape. This helps to make sure the cupcakes wont move while you are frosting.
If you opted for the sprinkle surprise, cut a small little circle 1/4 inch deep off the top of the cupcake, lift and put it to the side. Using a measuring spoon, fill the hole with sprinkles, then put the cupcake circle top back on and press down lightly.
Next- put the cake in the freezer for 10 minutes. This will make your frosting easier to smooth and also minimizes crumbs! Continue here if even if you didn't add the sprinkles.
Smooth the frosting all over the cake with a spatula (an offset one is best), or you can fill a piping bag with the chocolate buttercream and using a round tip, outline the border of the cake and then fill in the center with the rest of the buttercream.
To smooth the buttercream out, fill a clean spay bottle with water and lightly spray the cake. Smooth over the damp frosting with the offset spatula.
Finish up the decorating by adding white lines to either side of the football and lines in the center.