Pierogi z Serem i Ziemniakami - Sweet Cheese Pierogi

For dough: Place flour in large mixing bowl, make deep well in center.

Crack eggs into well, add pinch of salt and 1 tablespoon oil.

Gradually add warm water while mixing with fork, drawing flour from edges into center.

When dough becomes shaggy, turn onto floured surface and knead for 8-10 minutes until smooth and elastic.

Dough should be soft but not sticky - add flour or water as needed to achieve proper consistency.

Wrap dough tightly in plastic wrap, let rest at room temperature for 30 minutes to relax gluten.

For filling: Peel potatoes, cut into even chunks, boil in salted water 15-20 minutes until very tender.

Drain potatoes thoroughly, let steam dry in pot for 2 minutes to remove excess moisture.

Mash potatoes until completely smooth with no lumps using potato masher or ricer.

Pass farmer's cheese through sieve or food mill to remove any lumps and create smooth texture.

In large bowl, combine still-warm mashed potatoes with cheese, mix thoroughly.

Add sugar, egg yolk, and vanilla sugar, mix vigorously until filling is creamy and uniform.

Taste filling and adjust sweetness - can add more sugar if desired for sweeter version.

Let filling cool to room temperature before using - warm filling makes dough soggy.

Divide rested dough in half, keep unused portion covered to prevent drying.

Roll out dough on floured surface to 2mm thickness using rolling pin.

Cut out circles using 8cm round cutter or glass, re-roll scraps once.

Place 1 tablespoon filling in center of each circle, don't overfill or they'll burst.

Fold circle in half to create half-moon, press edges firmly together, pleat if desired for decorative edge.

Ensure edges are completely sealed with no gaps - press with fork tines for extra security.

Bring large pot of salted water to gentle boil, add 8-10 pierogi at a time.

Stir gently once immediately after adding to prevent sticking to bottom.

When pierogi float to surface, cook additional 2-3 minutes until puffy.

Remove with slotted spoon, drain well, place in serving dish.

Toss cooked pierogi with melted butter to prevent sticking.

Serve hot topped with sour cream and sprinkle of sugar, or just melted butter.