Classic Potato Cheese Perogi: Grandma's Secret Recipe

Instructions:

1. Prepare the Dough: Combine flour and salt in a bowl. Make a well, add egg, water, and oil. Mix until a shaggy dough forms. Knead on a lightly floured surface until smooth and elastic (about 5-7 minutes). Cover and let rest for 30 minutes.
2. Cook the Potatoes: Boil potatoes in salted water until tender. Drain and return to the pot.
3. Make the Potato Filling: Mash the potatoes with 2 tablespoons butter and warm milk. Stir in cheese, salt, and pepper. Set aside to cool slightly.
4. Caramelize the Onions: Sauté sliced onions in olive oil and butter over medium-low heat, stirring occasionally, until deeply golden brown and sweet (about 20-25 minutes). Stir in brown sugar and salt during the last few minutes.
5. Assemble the Pierogi: Roll out the dough thinly on a lightly floured surface. Cut out circles using a cookie cutter or glass.
6. Fill and Seal: Place a spoonful of potato filling in the center of each dough circle. Fold the dough over to form a half-moon shape, pinching the edges tightly to seal. Ensure no air is trapped inside. Crimp the edges with a fork for a decorative touch and extra seal.
7. Cook the Pierogi: Bring a large pot of salted water to a boil. Gently drop in perogi in batches (don't overcrowd). Cook until they float to the surface and cook for another 2 minutes. Remove with a slotted spoon.
8. Pan-Fry (Optional but Recommended): Melt remaining butter in a large skillet over medium heat. Pan-fry the boiled pierogi until golden brown and slightly crispy on both sides.
9. Serve: Top the pierogi with caramelized onions and a dollop of sour cream (optional).