1. In a bowl, mix flour with sugar, baking powder, cardamom, and salt. In a small bowl, beat egg to blend with milk and 2 tablespoons butter. Add liquids to dry ingredients and stir until evenly moistened.
2. Place an aebleskiver pan over medium-low heat. When pan is hot enough to make a drop of water dance, brush pancake cups lightly with melted butter and fill each to slightly below the rim with batter.
3. In about 1 1/2 minutes, thin crusts will form on bottoms of balls (centers will still be wet); pierce the crust with a slender wood skewer and gently pull shell to rotate the pancake ball until about half the cooked portion is above the cup rim and uncooked batter flows down into cup. Cook until crust on bottom of ball is again firm enough to pierce, about another minute, then rotate ball with skewer until the ridge formed as the pancake first cooked is on top. Cook, turning occasionally with skewer, until balls are evenly browned and no longer moist in the center, another 10 to 12 minutes. Check by piercing center of last pancake ball added to pan with skewer--it should come out clean--or by breaking the ball open slightly; if balls start to get too brown, turn heat to low until they are cooked in the center. Lift cooked balls from pan and serve hot (see notes). Repeat to cook remaining batter.
Nutritional analysis per pancake ball.