You’ll have to track down malt powder, which some stores don’t even carry these days. But if you ask the manager, he’ll probably be willing to special order it for you. Chill time is prep time. Cooking time is blending time.
Transfer the coffee to a small bowl and put it in the freezer just until it starts to turn icy at the edge, about 20 minutes. Stir, but leave it in the freezer for several more minutes, until you’re ready to use it.
While you’re at it, chill two tall drink glasses.
Put the milk, malted milk powder, and coffee ice cream in your blender.
Add the chilled coffee.
If you like your malted on the sweet side, add a tablespoon or two of the sugar.
Blend on medium speed to the desired consistency, then pour into the chilled glasses and serve.