Make cupcakes:

1. Make chocolate cupcakes according to recipe instructions and let cool completely before frosting.

Make mint buttercream frosting:

1. Bring a medium pot filled with one inch of simmering water to a boil. Place the egg whites and sugar in a stainless-steel bowl (like a stand mixer bowl). Use a whisk to beat the mixture until very hot (about 160° Fahrenheit).
2. Remove from heat and mix with the whisk attachment on high until it is cool, thick and glossy and has tripled in volume, about 5 minutes.
3. Reduce speed to medium and add butter a few pieces at a time. Set aside 1 cup of frosting for piping lines. 
4. Add the vanilla and peppermint extract and continue to beat until smooth and fluffy.*
5. Mix in green food gel coloring a tiny bit at a time until to desired color is achieved.

Decorate the Football Cupcakes:

1. Fit a piping bag with closed star piping tip and fill with green frosting. Holding tip perpendicular to cupcake surface, pipe “grass” by pressing out frosting and lifting straight up. Repeat until entire cupcake surface is covered.
2. Fit a second piping bag with the open hole piping tip and fill with the remaining uncolored buttercream and pipe three white lines on each (to represent field lines). Press a mini football onto the frosting.