Measure out the cooled, strong coffee and pour it into the blender.
Add the ice cubes to the blender, filling it up but leaving some room for blending.
Pour in the sweetener of choice, such as simple syrup or condensed milk, to balance the roasted coffee flavor.
Sprinkle in the vanilla extract to deepen the aroma and add a gentle sweetness.
Grate a small amount of lemon zest directly into the mixture for an unexpected burst of citrus brightness.
Secure the lid on the blender and blend on high until the mixture is smooth, frosty, and thick, about 30-40 seconds.
Check the texture—if it’s too thick, add a splash of water or milk and blend briefly to loosen it up.
Pour the icy coffee slushie into chilled glasses, making sure to scrape up any remaining frosty mixture from the blender.
Optionally, garnish with additional lemon zest or a sprig of mint for presentation.
Serve immediately with a straw or a spoon, enjoying the deep roasted aroma and icy crunch.
