In the bowl of your mixer, whisk together 1 cup warm water, 1/3 cup buttermilk, 1/2 Tbsp sour cream, 1 large egg, and 1 tsp salt, just until blended. Note: dough can be made by hand but the mixer is much easier.

Using the dough hook attachment, add 2 cups flour and mix on speed 2 until incorporated.

Add remaining flour 1/2 cup at a time allowing each addition to incorporate before adding more. Add the last bit of flour 1 Tbsp at a time just until dough no longer sticks to the sides of the bowl. Let the dough knead on speed 2 for 15 minutes. Dough will be soft elastic and feel slightly sticky to the touch, but won’t stick to your fingers.

Sprinkle a clean work surface with flour. Working with half of the dough at a time, roll it into a thin disk about 1/8" thick. Flipping the dough over once or twice while rolling will make it easier to work with. Cut the dough into circles using a cookie cutter or drinking glass with a 3" rim.

Place a round of dough in the palm of your hand with the stickier side up. Add 1/2 tsp sugar to the center and about 5 blueberries. Bring the edges together and pinch tightly to create a strong seal, making sure the sugar does not spill onto the edges. Transfer finished pierogi to a floured cutting board.

Blend the remaining scraps of dough into remaining dough half, and repeat steps 4 and 5 until all pierogi are finished.

In a large pot, bring 4 quarts water to a rolling boil and add 3/4 Tbsp salt. Carefully place half of finished pierogi in boiling water a few at a time (drop them close to the surface of the water to avoid hot splashes). Once pierogi float to the top, cook 1 1/2 to 2 minutes longer then remove with a slotted spoon and place into a colander to drain.

When plating pierogi, drizzle sugar in between layers of cooked pierogi to keep them from sticking to each other. The sugar will melt over the hot pierogies and turn into a light syrup. Serve with sour cream or eat them as is. These are best eaten fresh and warm :).