Mix together the flour, sugar, and salt in a bowl.
Make a well in the center and add the eggs. Whisk gently from the center outward until a thick batter forms.
Slowly pour in the milk while whisking to avoid lumps, until the batter is smooth and fluid.
Add the melted (not hot) butter and vanilla. Whisk until fully combined.
Let the batter rest for 30 min. at room temperature.
Heat a lightly buttered non-stick or crêpe pan over medium heat.
For each crêpe: Pour in a small ladle of batter and swirl to coat thinly. Cook 45–60 seconds, until edges lift. Flip and cook 20–30 seconds on the other side.