Batter: In a mixing bowl, add the flour and salt and make a well in the center. Add the eggs, milk, club soda and 3 tablespoons of melted butter into the center of the well and whisk together until just combined. The mixture should be like VERY loose pancake batter. If the mixture is a little thick, whisk in a little more milk. Let the batter sit for at least 30 minutes before using.
Melt about a 1/2 teaspoon of butter in a small nonstick saute pan. The butter should coat the bottom of the pan, if there is a lot of excess, wipe it out with a paper towel. Keep the paper towel handy in case you need it again (you will).
Put the pan over medium heat. Fill a 2-ounce ladle, almost to the top, with batter and pour it into the preheated pan, tipping and rolling the pan, as you ladle the batter, to evenly cover the bottom. This will take a little practice, even when you are an experienced crepe maker the first couple always get wasted. Accept it and move on.
When the edges of the crepe begin to pull away from the edges of the pan and the bottom begins to brown a little, turn the crepe over and cook it for about 1 minute on the other side. Remove the crepe from the pan to a plate and let cool. Stack the crepes as they are cooked between parchment paper squares. Repeat this process, until all the batter is used, wiping the pan with your paper towel or melting a little more butter to the pan, as needed.
*Crepe batter can be made up to 2 days in advance, covered and refrigerated.