Preheat your waffle iron to the desired setting (medium-high is usually ideal). Lightly grease with cooking spray or butter if your waffle iron isn't non-stick.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and salt until they are thoroughly combined and no lumps remain.

In a separate medium mixing bowl, whisk together the lightly beaten eggs, whole milk, melted and cooled unsalted butter (or vegetable oil), and vanilla extract until well combined.

Pour the wet ingredient mixture into the dry ingredient mixture. Whisk gently until just combined. A few small lumps are perfectly fine; be careful not to overmix, as this can lead to tough waffles.

Pour about 1/2 to 3/4 cup of batter onto the hot waffle iron, adjusting the amount based on your waffle iron's size. Close the lid and cook for 3-5 minutes, or until the waffle is golden brown, crispy, and steam stops escaping.

Carefully remove the cooked waffle from the iron. Serve hot immediately with your favorite toppings such as maple syrup, fresh berries, whipped cream, or a pat of butter. Repeat with the remaining batter until all waffles are cooked.