In a mixing bowl, cream together butter and sugar. Stir in the eggs, one at a time. Add vanilla. Stir in flour, mix until creamy.
Preheat Krumkake iron on both sides over medium to medium-high heat just until a drop of water sizzles on the surface; to prevent damage to the iron and to keep the cookies from scorching (Do not heat over the highest setting). Lightly grease the two sides of a Krumkake iron with cooking spray or melted butter. Alternative: If using an electric krumkake baker, follow the directions provided by the manufacturer.
Spoon 1 heaping tablespoon of batter onto the center of the iron. Close iron, squeezing handles together lightly to spread the batter (but not so tightly that the batter leaks down the sides of the iron). Bake for 30 seconds, flip iron over, and bake an additional 30 seconds. Flip iron back to initial position, open, and immediately roll cookie around a Krumkake cone or the handle of a wood spoon. Keep on roller until it is cool enough to keep from unfolding. Slip off cone and allow to cool on rack. Continue baking rest of dough. Store in tightly sealed container in order to retain crispness.
Cook's Note: If the first Krumkake appears lacy, full of holes or too thin, add slight amount of water.