In a bowl, mix together the flour, salt, yeast, brown sugar, and powdered milk.
Dilute with water, then add the vanilla seeds, carefully scraped out with the tip of a knife.
Cover the bowl with plastic wrap and let it rise for 1 hour.

In a tall-sided bowl, beat the egg whites until stiff, with a pinch of salt. Set aside.
Combine the cooled, melted butter with the previous mixture.
Then, gently fold in the beaten egg whites, being careful not to break them.

Preheat the waffle iron.
Using a ladle, pour a small amount of batter into the waffle iron and cook for about 5 minutes.