Quarter the apple, slice out the core and roughly chop it. Pop it in your blender. Roughly chop the cucumber and add that too. Peel the bananas and break them into the blender. Peel and chop the ginger and add it too, tucking in the spinach leaves as well.
Add 250ml cold water and a couple of ice cubes. Blitz till smooth, trickling in a little more water if you think it needs it. Serve straight away.