Add the limes and water to a blender and blitz for about 5 seconds. Too much will turn it bitter.
Strain the liquid into a bowl and discard the lime bits.
Add the condensed milk into the blender and add the lime water back in along with the ice.
Blitz for another 10 seconds until creamy and frothy!
Serve immediately
You can store it in the fridge for up to 12 hours but it will need to be blended again before serving (or whisk it)
