Directions

1. Place the potatoes in a medium saucepan and add water to cover by 2 inches.
2. Stir in 1 tablespoon salt.
3. Cover and bring to a boil over medium heat.
4. Uncover and cook until the potatoes are tender, about 10 minutes.
5. Drain the potatoes and return to the pan.
6. Place over low heat and stir for about 30 seconds to remove excess moisture.
7. Mash potatoes until very smooth.
8. Stir in the remaining 1/4 teaspoon salt, cheese, and 1 tablespoon of the cream.
9. Whisk 1 egg, yogurt, butter, and 1 teaspoon salt together in a medium bowl.
10. Pour the flour into a large bowl.
11. Pour in the egg mixture and gently stir into the flour.
12. Press and smash the mixture against the sides of the bowl with your palms, essentially kneading it within the bowl until it forms a ball.
13. Tip the dough and any remaining shaggy flakes out onto a clean work surface.
14. Knead until smooth, about 1 minute.
15. Cover the dough with the bowl and let rest 15 minutes.
16. Whisk 1 egg and 4 tablespoons water together in a small bowl.
17. Line a rimmed baking sheet with parchment paper.
18. Divide the dough into 4 pieces.
19. Roll one piece of the dough as thinly as possible into a rough 8 x 12-inch rectangle.
20. Using a 3-inch round cookie cutter, cut out 6 rounds of dough. Throw remaining scraps.
21. Spoon 1 teaspoon filling into the center of each dough round.
22. Swipe a very scant amount of egg wash around the dough edge.
23. Gently cup the pierogi in your hand in a U shape.
24. Gently but firmly seal the pierogi by pinching and squeezing the edges together with your thumb and pointer finger. Start with one pinch at the top, then move to one corner of the pierogi and pinch along the edge back to the top. Repeat on the opposite side to finish sealing the pierogi.
25. Transfer to the baking sheet.
26. Repeat with the remaining dough and filling.
27. Freeze on the baking sheet.
28. Add pierogies to boiling water and cook until floating, about 4 minutes.
29. Pan fry in butter or bacon grease.