Instructions:
- Plug in and preheat your waffle iron to medium-high heat, brushing lightly with oil or cooking spray if required by your model.
- In a large bowl, whisk together the flour, sugar, baking powder, and salt.
- In a separate bowl, whisk together the milk, egg yolks, melted butter, and vanilla extract until just combined.
- Pour the wet mixture into the dry ingredients. Whisk only until just combined. A few lumps are perfectly fine—do not overmix! Set aside to rest for 10 minutes.
- In a clean, grease-free bowl, beat the egg whites using an electric mixer until stiff, glossy peaks form.
- Gently fold about one-third of the whipped egg whites into the main batter to lighten it. Then, gently fold in the remaining whites in two additions using a rubber spatula, taking care not to deflate them.
- Pour the batter onto the preheated iron according to your machine’s instructions (usually filling 3/4 full). Close the lid gently.
- Cook until the steam subsides and the waffle is deep golden brown and crisp (usually 4–5 minutes). Do not open the iron early.
- Immediately transfer waffles to a wire cooling rack (not a plate) and serve hot.