This recipe requires a special pan (pictured below). They can be purchased at most specialty cooking stores, and I've seen them online at Target's website as well (called a Pancake Puff pan). The one we've always used is cast iron.
2 cups flour
2 teaspoons baking powder
1/2 teaspoon salt
1 tablespoon sugar
2 cups milk
1/4 teaspoon vanilla OR almond extract
4 tablespoons oil
oil for cooking
1. Combine the dry ingredients in a large bowl. Add the egg yolks, milk, extract, and oil. Beat with a wire whisk until frothy.
2. Beat the egg whites just until stiff peaks form. Carefully fold them in to the flour mixture. The batter should appear somewhat lumpy.
3. Heat the pan over moderate heat for about ten minutes or until droplets of water sizzle on pan's surface. Place a teaspoon of oil in each cup of the pan. Fill each cup with batter until nearly full.
4. When batter becomes bubbly, use a skewer or a fork (knitting needles or crochet hooks also work well here) to turn the aebleskivers inside the cup. At this point, you should be able to see the doughy inside of the aebleskiver.
Continue to turn them until they are cooked all the way around. (Although sphere-shaped, the aebleskivers often have an opening on one side. So don't worry if they are not entirely closed-it makes them easier to fill!)
5. Place cooked aebleskivers on a plate. They are traditionally filled with raspberry jam and sprinkled with confectioner's sugar, but you can be creative with you fillings if you like. They are definitely best eaten warm. Enjoy!