Heat the waffle maker according to the instructions that come with your machine.
Separate the yolks from the whites and place the whites in a large bowl.
Using an electric mixer, whisk the egg whites to stiff peaks.
In a separate large bowl, add the flour, bicarbonate, caster sugar, seeds from the vanilla pod and the salt and whisk (by hand) to incorporate.
Make a well in the centre and add the egg yolks and melted butter.
Start whisking until a smooth paste has formed add slowly add the milk.
Keep whisking until you get a smooth, thick batter.
Finally, carefully fold in the egg whites until you have a light batter frofthy batter.
Spoon the batter into your waffle maker and cook for 5 mins or according to the manufacturer's instructions.
Keep going until you've used all of the batter (they freeze well once cooked).
Add the first couple of batches to a baking sheet and keep warm in the oven (no higher than 100C).
Serve with your favourite toppings!