Brew the coffee however you prefer (pour-over, French press, Aeropress, traditional drip, any method will work).

Then while the coffee is brewing, combine the mint and sweetener in a cocktail shaker (or mason jar).  Use a muddler (or the end of a thick wooden spoon) to gently muddle the mint -- thoroughly enough so that those yummy minty oils get released, but also not so much that you break it up into a hundred tiny pieces that'll get stuck in your straw. ;)

Fill the shaker with ice.  Then pour the hot coffee over the ice, and add a splash of cream if desired.

Cover the shaker, and shake vigorously for 15 seconds until completely chilled.

Transfer the iced coffee to your serving glass (if using a separate glass).  Then add a few extra ice cubes if needed, garnish with a sprig of mint, and serve cold!