Combine flour, butter, and salt in a food processor.

Turn on the machine and slowly pour in warm water until a ball of dough forms.

Let the dough rest.

Cook the potatoes until tender.

Mash the potatoes and mix with shredded cheddar cheese until melted.

Let the filling cool slightly.

Roll out the pierogi dough with a rolling pin.

Use a glass or cookie cutter to make circles.

Dip the cutter in flour to prevent sticking.

Place a spoonful of filling on each circle.

Seal the edges well to prevent leaks.

Place the pierogies on a floured surface, ensuring they don't touch.

Bring a pot of water to a boil.

Drop 6-10 pierogies into the boiling water at a time.

Cook for 5-8 minutes, or until they rise to the surface.

Melt butter in an oven-safe dish.

Layer the pierogies with fried onions and bacon.

Bake until heated through (optional).