01 - Combine lemon juice, lemon zest, sugar, milk, vanilla extract, and ice cubes in a blender. Blend until completely smooth and frothy, about 30-45 seconds.
02 - In a clean, dry bowl, beat the egg white with cream of tartar until soft peaks form. Gradually add 2 tablespoons sugar while beating continuously until glossy, stiff peaks form.
03 - Divide the blended lemon mixture evenly between two tall glasses. Spoon or pipe the meringue topping generously over each drink.
04 - Sprinkle additional lemon zest and crushed graham crackers on top as desired. Serve immediately with straws and spoons.