In a large bowl, add the flour, eggs, salt, vanilla extract, melted butter, and sugar if used.
Using a whisk or electric mixer, beat in the milk gradually until a smooth batter forms with no lumps.
Heat a lightly buttered crepe pan over medium/high heat.
Pour or scoop the batter onto the pan, then tip and rotate the pan to spread the batter as thinly as possible.
Cook until lightly brown on both sides - about 1-2 minutes on each side and serve hot with your favorite fillings.