Whisk flour, baking powder, sugar, salt, cardamom and nutmeg together in a medium bowl. Set aside.
Whisk milk, egg yolks, vanilla and melted butter together in a large bowl until well combined. Add dry ingredients to wet ingredients and stir until just combined.
Place egg whites in the bowl of a stand mixer and, using the whisk attachment, whip until they come to medium peaks that are fluffy but not dry. Gently fold into the batter with a rubber spatula until just incorporated.
Heat an aebleskiver pan over medium low heat. Dot each round with a small cube of butter or brush with melted butter. Spoon a heaping tablespoon of batter into each round so that it is almost full. Cook until the bottom is just set, about a minute. Using a wooden skewer, gently turn each aebleskiver 90 degrees so that the batter spills out into the pan. Keep turning so that the side that is partially done is on the top. With the help of the skewer, continue cooking and turning until the aebleskiver are golden brown on all sides and a skewer inserted into the center comes out clean, about 6 to 8 minutes total. Adjust the heat downward if the æbleskiver are cooking too quickly.
Set aside on a wire rack to cool. Wipe out the pan with a damp paper towel and repeat with remaining batter. Dust with powdered sugar and serve warm with raspberry or strawberry jam if desired.