Directions

1. SLICE peeled potatoes into ½-inch rounds. Place potato slices into a medium saucepan, cover with water, and set over medium-high heat. When it comes to a boil, continue cooking for about 15 minutes or until potatoes are very tender. Remove from heat and drain potatoes.
2. RETURN potatoes to saucepan and add shredded cheese, 1 tablespoon butter, and salt. Mash by hand or use a hand-held mixer to blend until smooth and fluffy. Transfer potato mixture into a small bowl or baking dish, cover, and refrigerate for at least 30 minutes (the potato filling is easier to work with when it’s cooled).
3. COMBINE bread flour and salt in a medium mixing bowl. Make a well in the center and add eggs. Mix gently, adding water as needed, until the dough comes together (you may not use the full amount of water)
4. KNEAD by hand, either in the bowl or on a lightly floured surface just until the dough forms a firm ball, about 30-60 seconds. Lightly coat the ball in flour and cover (to prevent dough from drying out) and set aside for about 1 hour.
5. LINE a baking sheet with parchment paper or a silicone baking mat and set aside.
6. CUT dough in half when it is done resting. Keep one half covered in the bowl. Turn the other half onto a lightly floured work surface (a pasta machine is very useful here to roll out the dough). If the dough is sticky, sprinkle a little bit of flour over it and work it in gently without kneading. Roll out the dough to about ⅛-inch thickness. If the dough springs back a lot, allow it to rest for about 10 minutes and try again. Cut rounds in the dough with a 3-inch biscuit cutter or the top of a glass or jar.
7. REMOVE filling from the refrigerator. Using a spoon or tablespoon-sized cookie scoop, place a tablespoon of filling into the center of each dough round. Gently fold edges together, pinching the dough with fingers to achieve a good seal. Gently stretch the dough slightly to get it up and over the filling to pinch together. Avoid getting filling in the seal or the pierogi may open and leak while cooking!
8. PLACE finished pierogi on the lined baking sheet. Re-roll any scraps, allowing the dough to rest if it is difficult to roll at first. Repeat steps with other half of dough. There should be about three dozen pierogi. If there is any filling left, eat it with a spoon or save it for later. At this point, the pierogi may be frozen, or cooked from fresh.
9. FREEZE the baking sheet of pierogi until firm, and then transfer into a freezer bag or container until ready to use. Frozen pierogi can be kept for several months.
10. COOK the pierogi (either fresh or frozen) by setting a large saucepan of water over high heat and bring to a boil. Meanwhile, melt 4 tablespoons of butter in a skillet, over medium heat, add sliced onions, and cook until onions are browned. Carefully drop pierogi into boiling water (a half dozen at a time) and boil for 5 minutes. Transfer boiled pierogi into the skillet of butter and onions and toss to coat and keep warm. Serve with a little bowl of sour cream to dip into while they are still warm. Cover and refrigerate any cooked leftover pierogi and eat within 3-4 days.