In a large bowl, whisk together the flour, cocoa powder, sugar, and salt. If using the blender method, add wet ingredients to the blender first, then dry ingredients.

For the whisk method, make a well in the center and add eggs and vanilla. Whisk while slowly adding about half the milk to form a smooth paste. Then, whisk in the remaining milk and melted butter until smooth.

If using a blender, blend all ingredients on high for 30-45 seconds until completely smooth. Scrape down the sides and pulse once more.

Cover the batter and refrigerate for at least 30 minutes (or up to 48 hours). This step is crucial for tender crepes.

Heat an 8-inch non-stick skillet over medium heat. Lightly grease with butter.

Stir the rested batter. Pour about 1/4 cup of batter into the hot pan, then immediately lift and swirl the pan to spread the batter into a thin, even circle.

Cook for 60-90 seconds, until the edges are dry and lifting and the surface is matte. Gently loosen the edges and flip. Cook the other side for another 30-45 seconds.

Slide the cooked crepe onto a plate. Repeat with the remaining batter, stacking the crepes as you go to keep them warm.