Whip egg whites until frothy. Once frothy, increase the speed. As the egg whites begin to firm, gradually add sugar until incorporated and you have firm, glossy peaks and no grit (rub a little between your fingers to test).
Cut off the bottom edge of a zip lock bag to make a piping bag or use a store bought piping bag. Pour the meringue into the bag and pipe onto a baking tray with a non-stick liner or parchment paper.
Sprinkle crushed peppermints on top of each cookie.
Bake for 90 to 120 minutes or until the cookies are dry and airy.
Remove from the oven and let sit until completely cool.