In a mixing bowl, combine the flour, eggs, milk, melted butter, salt, and sugar if using. Whisk until the batter is smooth and free of lumps.

Let the batter sit for 15-30 minutes.

Preheat your non-stick skillet or crepe pan over medium heat.

Lightly grease the pan with a bit of butter or oil.

Pour about ¼ cup of batter into the center of the pan. Quickly tilt and swirl the pan to spread the batter evenly into a thin layer.

Cook for 1-2 minutes, or until the edges start to lift and the bottom is lightly golden.

Using a spatula, gently lift the crepe and flip it over. Cook for an additional 30 seconds to 1 minute until it sets fully.

Transfer the cooked crepe to a plate and repeat with the remaining batter, greasing the pan as necessary.