I used this æbleskiver recipe from a Danish enclave in MN at Lutsen, but I cut it in half for two people. They recommend allowing 7 puffs per person, which is handy because that's how many fit in a pan. The recipe below makes ~18 puffs.
For the technique, watch this video from Solvang:
1 c. buttermilk
2 eggs, separated
1 Tbsp. sugar
1 Tbsp. oil
1 pinch salt
1 c. flour
1/2 tsp. baking powder
1/2 tsp. baking soda
Beat the egg whites until stiff. Whisk together the yolks, sugar, oil, and salt in a large measuring cup with a pour spout. Sift together the flour, baking powder, and baking soda and then add it to the liquid ingredients. Whisk until very smooth. Gently fold in the egg whites.
Heat the pan over medium heat. You want it to give you a little sizzle when you pour in the dough, but not too hot or the æblesiver will cook too quickly. Add a small pat of butter to each hole and swish it around with a pastry brush, brushing some butter on the flat surfaces as well.
Pour batter into each hole until its about 90% full. Use a skewer or knitting needle (which you will use later for flipping them) to cut the batter between pours. By the time you finish filling the holes it will be almost time to start turning them.
Use your skewer to loosen the edges of the dough, and then turn each puff 90° onto its side. Then go through and rotate them two more times so that they cook in sphere shape (go watch the video to see how this is done). You can continue to brown and turn them if they aren't golden enough.
In Solvang they're typically served with raspberry jam and powdered sugar, but you can put any tasty thing you like. Enjoy!