Perfect Pierogies - cooking recipe

Ingredients

Dough
3 cups all purpose flour
1/2 teaspoon salt
3/4 cup warm water
1 egg, beaten
1 tablespoon vegetable oil
Filling
1 1/2 lbs russet potatoes, peeled and cut into chunks (about 3 large)
1/4 cup butter
1 large onion, chopped
1/4 cup milk
salt, and ground black pepper.
garlic powder, to taste
1/2 cup shredded cheddar cheese
egg wash
sour cream, for serving

Preparation

For the dough: In a medium mixing bowl stir together all of the dough ingrediants until smooth. Turn dough onto a floured surface and knead just until dough comes together, 1 to 2 minutes. Wrap dough in plastic wrap and chill for at least 30 minutes.
For the filling: In a skillet cook onion in butter until soft. Cook potatoes in salted boiling water until tender, drain. Transfer potatoes back to pot and mash until smooth. Stir in cooked onion with butter, milk, salt, pepper, and garlic powder. Let cool. Then stir in cheese.
To assemble: Divide dough into 4 pieces. On a floured surface roll out 1 piece of dough as thin as possible. Using a 3 inch round cookie cutter dipped in flour, cut out rounds of dough. Repeat with other dough pieces. Keep cut circles covered so they don't dry out. Place a spoonful of filling on one half of each dough circle. Using your finger, wet the the edges of each circle with egg wash. Bring dough edges together to form a semi circle. Press edges together with a floured fork. Place pierogies onto a cookie sheet to keep seperate them or they will stick.
To cook: In a large pot of salted boiling water for about 7 to 8 minutes. They can be frozen just cook them for a couple minutes longer. Serve pierogies with sour cream. Enjoy!