Plug in your waffle iron and turn it on to preheat.
In a large bowl, whisk together the flour, baking powder, and salt.
Carefully crack the eggs, separating the yolks from the whites.
Using an electric mixer fitted with the whisk attachment, beat the egg whites in a separate bowl until stiff peaks form. This means that when you lift the whisk, the peaks hold their shape and don’t droop.
In a separate bowl, whisk together the milk, vanilla and egg yolks.
Pour the milk and egg yolk mixture into the dry ingredients. Whisk to combine the ingredients. Don’t overmix! A few lumps are okay.
Stir in the slightly cooled melted butter.
Gently fold the beaten egg whites into the batter. Leave little fluffs of them showing in the batter.
Pour enough batter onto the center of the lower grid to spread to about 1 inch from the edges. Gently close the lid and don’t open it while the waffle cooks.
Cook according to your waffle iron’s instructions. For those with adjustable waffle irons, a higher heat setting will create crispier waffles.
Carefully remove the waffle from the iron with a fork and place it on a cooling rack to cool or serve warm. Repeat steps 8-10 to cook the remaining batter, preheating your waffle iron between batches.