Recipe video above. Pierogi Ruskie's are Polish dumplings filled with cheesy, creamy mashed potatoes served with an onion butter sauce. They are even more delicious than they sound! Traditionally made with quark which is an European fresh cheese which isn't easily found in Australia, so I've used cheddar because I want this recipe to be as accessible as possible to many people to experience the greatness that is Pieorgis!!! More in Note 2.Excellent weekend project – eat some today and freeze some for later (they cook from frozen). Makes a nice big batch of 30 pierogis. For more dumplings of the world - head here!