Classic Potato and Cheese Pierogi with Caramelized Onions

1.Prepare the Filling: Place the peeled potatoes in a large pot, cover with cold, salted water, and bring to a boil. Cook until fork-tender, about 15-20 minutes. Drain thoroughly and mash until completely smooth. Let the mashed potatoes cool slightly.

2.Mix the Filling: In a bowl, combine the mashed potatoes, shredded cheddar cheese, cottage cheese (if using), melted butter, 1/2 teaspoon salt, and 1/2 teaspoon pepper. Mix well until fully incorporated and set aside.

3.Make the Dough: In a large bowl, whisk together the flour and 1 teaspoon of salt. Create a well in the center and add the egg and vegetable oil. Gradually pour in the warm water, mixing until a shaggy dough forms. Turn the dough out onto a lightly floured surface and knead for 5-7 minutes until smooth and elastic. Cover the dough with plastic wrap or a damp towel and let it rest at room temperature for at least 30 minutes.

4.Assemble the Pierogi: Divide the dough into two equal pieces. Keep one piece covered while working with the other. Roll the dough out thinly (about 1/8 inch thick). Use a 3-inch round cookie cutter or the rim of a glass to cut out circles.

5.Place about 1 teaspoon of filling in the center of each dough circle. Fold the dough over to form a half-moon shape. Pinch the edges tightly to seal, ensuring no air pockets remain. For a decorative edge, you can crimp the sealed edge with a fork or create a rope braid.

6.Boil the Pierogi: Bring a large pot of salted water to a rolling boil. Gently drop the pierogi into the boiling water, working in batches so as not to overcrowd the pot. Stir gently to prevent sticking.

7.Cook the pierogi until they float to the surface, then continue to boil for an additional 2-3 minutes. Remove the cooked pierogi with a slotted spoon and place them on a lightly oiled plate or baking sheet to prevent sticking.

8.Pan-Fry: In a large skillet, melt 6 tablespoons of butter over medium heat. Add the thinly sliced onions and 1/2 teaspoon of salt. Sauté slowly, stirring occasionally, until the onions are deeply golden brown and caramelized, about 10-15 minutes.

9.Add the boiled pierogi to the skillet with the onions and butter. Pan-fry for 3-4 minutes per side until the dough is golden brown and slightly crispy. Serve immediately, topped with the caramelized onions and extra melted butter from the pan.