Prepare the Batter:
Add eggs to blender first, followed by milk, flour, sugar, melted butter (slightly cooled), and salt.
Blend on medium-high speed for 1 minute until smooth and uniform.
Stop and scrape down sides with spatula. Blend another 10 seconds to ensure no flour clumps remain.
Transfer batter to bowl or pitcher, cover, and refrigerate for at least 1 hour (2 hours recommended, or overnight).
Cook the Crepes:
Heat an 8-10 inch nonstick skillet or cast iron pan over medium heat for 3 minutes.
Test heat by sprinkling water drops on surface - they should sizzle and evaporate quickly.
Add 1/2 teaspoon butter to pan, swirl to coat, and wipe out excess with paper towel.
Stir chilled batter gently. Pour 1/3 cup batter into center of pan.
Immediately lift pan off heat and tilt in circular motion to spread batter thinly across bottom.
Return to heat and cook for 30-45 seconds until edges look dry and bottom turns golden brown.
Use offset spatula to gently flip crepe. Cook second side for 15-20 seconds.
Slide crepe onto plate and cover with clean kitchen towel to keep warm.
Lightly butter pan before each crepe. Repeat process until all batter is used.