Separate the egg yolks and the egg whites. The egg whites go into a bowl for whisking later.
Whisk together the egg yolks with the milk and vanilla extract.
In a separate bowl, mix the flour, sugar and salt. Make a well at the centre.
Pour the milk mixture into the centre of the dry ingredients. Use a whisk to mix these two starting at the centre and slowly incorporating the flour from the sides.
Whisk the egg whites until they are stiff.
Add about ⅓ of the egg whites to the previous mixture and use a spatula and folding motions to incorporate them. Repeat this with the other two thirds of egg whites.