Prepare Batter – In a blender, combine flour, eggs, milk, melted butter, sugar (if using), and salt. Blend until smooth. Let the batter rest for 20 minutes to relax the gluten.
Heat Pan – Warm a nonstick skillet or crepe pan over medium heat and lightly grease with butter.
Cook Crepes – Pour about ¼ cup of batter into the pan, quickly tilting to spread it into a thin, even layer.
Flip Crepes – Cook for 1 minute until the edges lift easily, then flip and cook another 30 seconds.
Repeat – Stack cooked crepes on a plate with parchment paper between each to prevent sticking.