Preheat your Belgian waffle maker according to manufacturer's instructions.

Whisk flour, sugar, baking powder, and salt in a large bowl.

Beat egg whites to stiff peaks in a separate bowl; set aside.

Whisk yolks, milk, melted butter, and vanilla in another bowl.

Stir wet into dry just until combined; batter will be slightly lumpy.

Gently fold in beaten whites until incorporated.

Pour batter onto hot waffle iron; cook according to manufacturer until golden and crispy, about 4-5 minutes per waffle.

Serve immediately with butter, maple syrup, fresh berries, or whipped cream.