Pour the caramel syrup into the blender, making sure it’s smooth and slightly cooled to avoid clumping.
Add the ice cubes to the blender, filling it about three-quarters full to create a thick, icy base for the slushie.
Pour in the milk to help blend the ice smoothly, adding a little more if the mixture seems too thick or starting to clump.
Secure the lid on the blender and blend everything on high speed for about 30-45 seconds, until the mixture is thick, smooth, and velvety, with a glossy appearance.
Stop the blender and check the texture — it should be creamy yet scoopable; if it's too slushy, add a few more ice cubes and blend briefly.
Pour the caramel slushie into chilled glasses, and garnish if desired with a drizzle of caramel or a light sprinkle of sea salt for extra flavor.
Savor immediately with a straw or spoon, enjoying the cool, rich caramel flavor and the satisfying slushy texture.