Preheat waffle iron.
In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
In another bowl, whisk eggs, buttermilk, melted butter, and vanilla.
Add wet ingredients to dry, stir until just combined—do not overmix.
Spray waffle iron with oil and pour in batter.
Cook until golden brown. Repeat with remaining batter.
Serve fresh or let cool and freeze for later.