1. Into a small saucepan, sprinkle unflavored gelatine over 1/4 cup milk and let it stand 1 minute.
2. Over low heat stir such that the gelatine is completely dissolved, about 5 minutes.
3. Using a blender, process remaining 1/4 cup milk, syrup, sweetener and vanilla until blended.
4. Through the feed cap while processing, , slowly add gelatine mixture and process until blended.
5. Put in ice cubes, 1 at a time and process at high speed until ice is melted.