In a blender jar, blend together cold brew coffee concentrate, milk, sugar, and ice cream for about a minute on slow speed.
Now keep a glass drizzled with dark chocolate syrup ready for serving.
Add ice cubes, you can add plain ice cubes or if you want the stronger flavor you can add ice cubes made with cold brew concentrate.
Pour the coffee in over ice cubes in two tall glasses. You can serve it as it is or top it with one scoop of ice cream and chocolate syrup and serve it immediately.