Wow ! I made it with a great gin, and since there was no indication for the bitter, I chose Lejay blackcurrant (I love basil and red fruits combined), it's outstanding, and my wife loves it as well !
Definitely a great reason to plunder the basil plants! Five leaves is really subjective since they can be as big as your thumb! I err on the side of more basil (lots) and Navy strength gin. Fresh egg white gives a much better meringue on top. For sure my favorite until the basil peters out lol.