Get the pan heating over medium-low to medium heat.In a large mixing bowl, stir together the flour, sugar, baking soda, cardamom and salt. Add the egg yolks, lemon zest, vanilla, and buttermilk and mix until smooth. Add the melted butter (not super hot) and mix until combined.In a separate bowl, beat the egg whites until stiff peaks form. Fold the egg whites into the batter. Gently break up any large lumps but it's fine if a few small ones remain.

Place a little butter into each of the hollows of the pan. Butter produces the best flavor but you can use oil instead.Once hot pour the batter into each well, filling them nearly full. Let the batter cook until it begins to bubble around the edges. Use a wooden or metal skewer (the traditional tool is a knitting needle) to push against the side of each well and gently turn each aebleskive 90 degrees. As you do this the batter will spill into the bottom of the well.Once the batter begins to bubble around the edges, give it another 90 degree turn. Repeat this step again, giving the aebleksiver another turn.At this point you can then finish the aebleskiver with one final turn or you can first "top off" the aebleskiver by piping or spooning a little extra batter into the center before making the final turn. This will ensure that the very bottom of the ball is sealed.Give the aeblekisver the final turn to complete the full sphere. If your aebleskiver are not quite as browned as you like, you can continue to rotate them until they're browned to your liking.

Serve the aebleskiver immediately while they're hot. Place them in a bowl at the table, letting guests help themselves. To serve them like the Danish, each guest should have a small mound of powdered sugar and jam on their plates with more at the table for refills. The aebleskiver are eaten with your fingers, first dipped in the jam followed by the powdered sugar (the jam helps it to adhere).