You do not need to use instant coffee, you can brew a strong cup of your favorite coffee and freeze it, just make sure it's 1½ cups.
If coffee is to frozen for your blender to handle let it sit on the counter for a few minutes to thaw out.
Calories: 43.3, Fat: 0, Sodium: 65, Carbs: 7, Sugar: 6, Protein: 4.2