If you don’t let crepe batter rest, the crepes will be dense and rubbery, as the gluten in the batter will not have had time to relax and allow the batter to expand and become light and fluffy. It is best to let the crepe batter rest for at least 30 minutes before cooking, as this will allow the flavor to develop and the texture to become light and creamy. If you don’t have time to let the batter rest, you can try adding a tablespoon of baking powder to the batter, as this will help to create a lighter texture.