Brew the coffee using a French press, or a steel strainer basket of coffee for brewing a single cup. The coffee goes in the basket, and gets immersed in a cup of hot water.
Fill a glass with ice. I like big ice cubes. Use an empty pudding or fruit cup container for a mold. If you are looking for something fancier, you can get silicone molds for ice spheres or cubes.
Pour hot coffee over ice.
Stir in condensed milk.