Making Homemade Pierogies on Christmas Eve

Link to pierogie recipe: dishfunctionaldesigns.blogspo...
First make the dough:
2 cups flour
3/4 cup sour cream
1 large egg
1/4 cup olive oil
1/2 teaspoon salt (kosher or sea salt are best)
Mix all ingredients together to form a dough.
Knead dough on a lightly floured surface for a few minutes until smooth.
Wrap dough in plastic wrap and place in refrigerator for about 30 minutes while you make the filling.
Next make the filling:
1 pound potatoes, peeled and cubed (I use 3-4)
1 cup grated sharp cheddar cheese
1 Tablespoon butter
2 Tablespoons milk
Salt and pepper to taste
Place cubed potatoes in pot, cover with water, and add 1 teaspoon salt to the water. Cover and simmer until potatoes are fork-soft, about 10-15 minutes. Drain potatoes and add to mixer (you can also mash them by hand in the pot using a potato masher if you prefer.)
Add 1 T. butter, the shredded cheese, 2 T. milk, and salt and pepper to the potatoes and mash until smooth.
Now let's make the perogies:
Roll out the dough on a lightly floured surface.
We split our dough into two balls and rolled them out one at a time to make it more manageable.
I like to roll it to just under 1/8 in thickness. Not too thin or you will get holes in your pierogies -too thick and they will be too doughy. Practice makes perfect!
Use the rim of a glass, cup or cookie cutter to cut circles from the dough that are about 3 inches in diameter. Use your fingers to press the dough circles a little larger if needed. Our first ones were a bit thick so we either stretched them out a bit, or re-rolled them.
Now it's time to fill them! Get a custard cup or small bowl of water for your workspace. Scoop up about a tablespoon size dollop of filling and roll into a ball. Place filling inside your dough circle. Brush the edges of your dough circle with a few drops of water. Fold one side of your dough circle over to create a half-moon shape.
Press down on the edges to seal, making sure to also gently press the air out. Use a fork to gently seal the seams.
Fill a large soup pot about 2/3 full with water and bring to a rolling boil. Add about a teaspoon of salt to the water. Once the water is boiling, carefully add your pierogies, in batches of 5 or 6 at a time, and boil for about 3-4 minutes.
Remove the pierogies from the boiling water with a slotted spoon. I place mine in a colander that is on a plate to drain them. Next, drizzle the cooked pierogies with a tablespoon or two of olive oil so that they do not stick together!