Combine the flour, sugar, baking soda, baking powder, and salt in a medium bowl and stir using a balloon whisk to combine.
Add the wet ingredients: buttermilk, butter, and vanilla, and mix until smooth. Do not over mix; otherwise, the waffles will be heavy when cooked.
Let the batter rest at room temperature for 10 minutes.
Preheat a waffle iron according to the manufacturer's instructions.
Spray the waffle iron with non-stick cooking spray.
Pour the batter into the waffle iron and cook according to the manufacturer's instructions, usually for 2 to 3 minutes.
Place in a 200º F (95º C) oven to keep waffles warm while you finish with the rest of the batter.