01 - Place the chilled watermelon cubes in a blender container.
02 - Pour in milk, vanilla ice cream, and sweetener if using.
03 - Add lime juice for a tangy flavor variation, if desired.
04 - Blend on high speed until completely smooth and creamy, approximately 30-45 seconds.
05 - Add ice cubes and blend again for a frostier consistency, if preferred.
06 - Pour into tall glasses and serve right away while chilled.