Boil potatoes until soft. Mix cheese with potatoes and mash. Let cool. Fry onions in butter. the potatoes can be made a day ahead of time and kept in the refridgerator. To make the dough beat the eggs then add water. Add this to flour. Knead to make a very stiff dough. Roll out 1/16 thick. Cut with pierogi maker, dumpling maker, or any round cutter. Add potato mixture according to the size of the round, fold over and seal. Put in a large kettle of boiling water. let pierogi rise to surface. Spoon into a large bowl and pour butter and onion mixture over each layer. For a change of flavor you can add pepper, onions, garlic, or all three to the mashed potatoes. Let each person season with salt if desired. The prep and cooking time depends on the size you make as does the quantity and number of servings. gramndma Kiszka didn't have a written recipe and used her judgement on quantities. Her daughters figured out the measurements to make things easier for future generations in this country. It was passed on to my mother and all the wives of their brothers as they married. They are good hot or cold and grampa Kiszka often took them with him in the coal mine for his meal during his shift.