Place water, softened butter, egg, egg yolk, milk powder, potato flakes, sugar, salt, flour and yeast in the pan of the bread machine in the order recommended by the manufacturer. Select Dough cycle; press Start. Check dough after 5 minutes of mixing, adding 1 to 2 tablespoons of water if necessary.
When the cycle is complete, spoon out dough with tablespoon and roll into walnut sized balls. Place 2 inches apart on a lightly greased cookie sheet. Cover and let rise until doubled, about 1 hour.
Flatten balls slightly with the palm of your and make a depression in center with your thumb. Fill with 1 tablespoon of filling. Cover and let rise for about 30 minutes. Meanwhile, preheat oven to 375 degrees F (190 degrees C).
Bake in preheated oven for 13 to 15 minutes, until lightly browned. Remove from oven and brush with melted butter. Cool on wire rack.