Place the ice cubes into the blender.
Pour the chilled Sprite soda over the ice in the blender.
Secure the lid on the blender and blend on high speed until the mixture is smooth and frosty, about 30-60 seconds.
Stop the blender and check the consistency; it should be thick and slushy, with tiny ice crystals visible.
Taste and, if desired, add a splash more soda for extra flavor, then blend briefly again to incorporate.
Pour the slushie into glasses, using a spoon to help serve if needed, and enjoy immediately for best texture.