In a mixing bowl, whisk together the flour, sugar, and cardamom (if using).
Gradually stir in the melted butter and heavy cream until a smooth batter forms. Let the batter rest for about 30 minutes.
Preheat your Krumkake iron according to the manufacturer's instructions.
Place a tablespoon of batter onto the center of the iron, close the lid, and cook for about 30-60 seconds or until golden brown.
Carefully remove the cooked Krumkake using a spatula and immediately roll it into a cone shape around a cone-shaped form or the handle of a wooden spoon.
Allow the Krumkake to cool and set in the cone shape before removing.
Repeat with the remaining batter.
Once cooled, you can fill the Krumkake with whipped cream or any other desired filling.
Enjoy!