In a large mixing bowl, whisk together the gluten-free all-purpose flour, sugar, baking powder, and salt until fully integrated. Set aside. In a separate medium bowl, combine the melted butter, milk, eggs, and vanilla extract, blending until smooth. Gradually incorporate the wet mixture into the dry ingredients, mixing continuously to ensure a lump-free batter. Preheat the waffle maker and allow the batter to rest during this time. Once preheated, lightly coat the waffle plates with gluten-free cooking spray. Portion batter using a ladle or cookie scoop, adjusting the quantity to fit your specific waffle maker. Close the lid and cook as per appliance instructions, or until waffles are evenly golden and fully cooked. Carefully extract the waffles using a fork and place them on a plate. Repeat with the remaining batter. Serve warm with toppings of your choice, or allow to cool before refrigerating or freezing for future enjoyment.