Stir the milk into the hot coffee. Let the sweetened coffee sit until room temperature and then fill two ice trays with the sweetened coffee. Place the trays in the freezer until frozen solid. Pour the remaining coffee mixture into a jar and refrigerate until chilled.
For each milkshake, place 8 sweet coffee ice cubes and 1 cup of the coffee mixture in the blender. Blend until thick. Pour into a glass and serve. Enjoy!
The coffee mixture will keep nicely in the refrigerator for several days. Stir it together now and you'll be able to blend the perfect iced coffee whenever you want.