Peel, wash and dice the potatoes and cook them in salted water. Drain and press hot through a potato press.
Finely dice the onions and bacon. Put both in a saucepan, leave out the bacon in it and let the onions become translucent. Then add to the potato mixture.
Finely chop the chives and add to the potato mixture with the 3 egg yolks. Knead all ingredients into a smooth dough, shape into a ball and let rest in a cool place for 30 minutes.
Shape the dough into sausages as thick as a finger. Heat the butter in the pan and bake the sparrows in portions until golden brown on all sides.