In a bowl, whisk together 2 cups flour, 1 teaspoon baking powder, 1/2 teaspoon salt, and 1 tablespoon sugar.

In a separate small bowl, lightly whisk the egg yolks from 4 eggs.

Whisk in 2 cups milk (buttermilk recommended) and 4 tablespoons of melted and cooled unsalted butter into the yolk mixture.

Whisk the yolk mixture into the flour mixture until just combined. The batter will be lumpy.

In another bowl, using an electric mixer, beat the egg whites from 4 eggs on high speed until stiff but not dry peaks form (about 2-3 minutes).

Gently fold the beaten egg whites into the batter in two additions using a rubber spatula.

Put 1/4 teaspoon butter in each well of the Ebelskiver pan.

Set the pan over medium heat until the butter begins to bubble.

Pour 1 tablespoon of batter into each well.

Cook until golden brown on the bottom and cooked halfway through, then flip.

Cook until the Ebelskivers are golden brown and cooked through.

Remove from the pan and serve immediately with desired fillings and toppings.