Farmer's Cheese Pierogi with Browned Onion Butter

Steps

1. Make the dough first: in a bowl mix the flour with one-third of the salt. Add the sour cream, egg and lukewarm water and stir into a shaggy dough.
2. Knead the dough on a lightly floured counter for 5 minutes until smooth and soft, then cover and rest it for 30 minutes while you make the filling.
3. For the filling, put the red potatoes in a pot, cover with cold water, add another third of the salt and boil 15 minutes until very tender. Drain and mash until smooth.
4. Stir the drained cottage cheese, Parmesan and black pepper into the warm potatoes. Let the filling cool for 10 minutes.
5. For the onion butter, melt half the butter in a large skillet over medium-low heat. Add the onion and cook, stirring often, 20 minutes until deep golden. Scrape into a bowl and keep the skillet.
6. Roll the rested dough very thin, about 1/16 inch, and cut 3-inch rounds; reroll scraps once. You should get about 32 rounds.
7. Place a heaping teaspoon of filling on each round, fold into a half-moon and pinch the edges firmly to seal.
8. Bring a large pot of water to a boil with the remaining third of the salt. Boil the pierogi in batches, 3 minutes after they float, and lift out with a slotted spoon.
9. Melt the remaining half of the butter in the skillet over medium heat. Add the boiled pierogi and fry 2 minutes per side until golden in spots.
10. Return the browned onion to the skillet and toss with the pierogi. Serve sprinkled with the parsley.