First, plug in your waffle iron and set it to the recommended temperature, so it’s hot and ready when your batter is done.

In a mixing bowl, combine the flour, baking powder, baking soda, sugar, and cocoa powder. Use a whisk to blend them together well, then set the bowl aside.

In a large measuring cup or another bowl, combine the vanilla, milk, egg yolks (the yellow part of the eggs), and melted butter. Stir these together until everything is well mixed.

Pour the wet mixture into the bowl with the dry ingredients. Stir until everything is fully combined and you have a smooth batter.

In a clean bowl, whip the egg whites using a hand mixer until they form stiff peaks—this means the egg whites should hold their shape when you lift the beaters out of the bowl.

Gently fold the whipped egg whites into your batter using a spatula. This will make your waffles light and fluffy. Be careful not to overmix.

Pour the batter into your preheated waffle iron. Close the lid and cook until the waffles are golden brown. The exact time will depend on your waffle iron, so check the manufacturer’s instructions if you're unsure. When done, carefully remove the waffle and enjoy with your favorite toppings!