¾ oz sloe gin¾ oz dry gin¾ oz lemon juice½ oz simple syrup (1:1)1 egg whitesoda water
instructions :

Add an oz or so of soda to a fizz glass or coupe.

Add sloe gin, gin, lemon juice, simple syrup and egg white to a cocktail shaker.

Shake without ice.

Add ice and shake until well-chilled.

Strain into prepared fizz glass or coupe over top of soda and observe the fluffy foam.

source :
punchdrink.com