Measure out the brewed coffee and let it cool to room temperature or chill in the fridge.
Add the ice cubes to your blender and pour in the cooled coffee.
Blend the mixture on high speed until the ice is completely crushed and the mixture is smooth and frothy.
Stop the blender and check the texture; it should be thick, creamy, and frosty. If needed, add a few more ice cubes and blend again until desired consistency is reached.
Pour the coffee slushie into glasses and serve immediately for the best icy texture.