For the filling, stir together filling ingredients until just combined and set aside. When ready to use, drain all liquid from apples using a fine sieve.
In a medium mixing bowl, mix together flour, baking powder, sugar and salt; set aside.
In another medium mixing bowl, whisk together egg yolks, milk and 2 Tbsp. of melted butter. Add dry ingredients to wet and stir to combine.
In a third medium bowl, whisk egg whites until stiff but not dry, about 2 - 3 minutes. Fold egg whites gently into batter mixture until incorporated.
Preheat an ebelskiver pan over medium heat for about 1 minute; when pan is hot reduce heat to low.
Place about 1 Tbsp. of batter mixture into each indentation, then add 1 tsp. of filling and cover with another Tbsp. of batter.
Cook for about 2 minutes or until the edges of the pancake turn golden brown; flip quickly using a fork or wooden skewer to push down on one side and cook for another 2 minutes.
Remove to clean plate, allow to cool and dust with confectioners’ sugar.
Repeat process until all batter is used.