Making crepe batter is quick and easy. Simply combine all of the wet ingredients in a blender, add the dry ingredients, and blend briefly. Then cover the batter and let it rest, chilled, for one hour. Harold McGee, author of On Food and Cooking
, explains that this allows "the proteins and damaged starch to absorb water," ensuring the crepes will be tender. The air incorporated into the batter will also dissipate, so the crepes will be paper-thin. After the crepe batter rests, stir it with a whisk to make sure the flour is evenly dispersed, and stir occasionally throughout the cooking process for the same reason.
It's important for the batter to reach the right consistency―similar to that of heavy whipping cream. This produces a thin, even crepe with enough structure to hold together. Different flours or types of milk, the amount of fat, and other factors have a subtle impact on the final consistency.