Whisk the flour, sugar, baking powder, and salt together in a large bowl.
In a separate bowl, lightly beat the egg yolks, then add the milk and melted butter. Mix well to combine.
Add the wet ingredients to the dry ingredients and stir just until combined. It's okay if some lumps remain.
In another bowl, beat the egg whites with until fluffy and stiff peaks begin to form. This can be done by hand, but is much easier with a mixer. Gently fold the egg whites into the batter using a rubber spatula. It's okay if there are still some streaks of egg white showing.
Cook in a preheated belgian waffle iron until golden brown. Be careful not to overfill the waffle maker as the batter with puff and spread while it bakes. Transfer finished waffles to plates to eat immediately, or place on a wire rack while cooking the rest of the batch so they don't steam on the bottom and lose their crispness.
Top with syrup, freshly whipped cream, berries, nutella, or any toppings you like. Enjoy!
