Turn on your waffle iron and let it get fully hot while you mix. A properly preheated iron is the difference between crisp and sad.
In a medium bowl, stir together the flour, baking powder, sugar, and salt.
Pour in the milk, melted butter, and vanilla. Whisk just until combined. A few small lumps are fine; overmixing makes tough waffles.
Lightly grease the iron if needed, pour in the batter, and close. Cook 3 to 4 minutes until golden and crisp and no more steam escapes.
Move the waffle to a warm plate. Add your toppings, keep the portion modest, and enjoy while it's hot.