Whisk Together Dry Ingredients
In a large mixing bowl, combine the flour, sugar, baking powder, baking soda, and salt. Whisk for about 30 seconds until evenly distributed.
Combine Wet Ingredients
Create a well in the center of the dry ingredients. Pour in the cold milk, melted butter, vanilla extract, and beaten eggs. Whisk until the batter is smooth and consistent, resembling thick pancake batter. Don't overmix a few small lumps are fine.
Preheat the Waffle Maker
Turn on your Belgian waffle maker and let it heat completely until the indicator light shows it's ready. Brush the waffle plates generously with melted butter to prevent sticking.
Pour and Cook the Batter
Pour about 1/2 cup of batter into the center of the preheated waffle maker. Close the lid gently but firmly. Cook for 3-5 minutes or according to your waffle maker's instructions, until the waffle is golden brown and releases easily.
Repeat and Keep Warm
Repeat with remaining batter. Keep finished waffles warm in a 200°F oven placed directly on the oven rack while cooking the rest.
Serve
Transfer warm waffles to plates and top with your favorite toppings such as butter, maple syrup, fresh berries, whipped cream, or powdered sugar.