First make a pot of blue pea flower tea – let it steep until the color is really an intense blue.
Leave the tea to cool then freeze to make ice cubes. Once these are solid, crush them in a powerful blender until you have blue crushed ice. You can keep this in a jug in the freezer until you need to use it.
Shake the cranberry juice, gin, St Germain and lemon juice in a cocktail shaker half filled with ice,
Fill two glasses with ice cubes and then divide the cocktail between the glasses.
Top with the blue crushed ice which will gradually turn purple as it melts!
Place cocktail cherries (or blueberries!) inside fresh or tinned lychee to create the eyeballs and thread them on a cocktail stick to garnish.