Homemade Pierogi and Hotdogs and Philly Cheese steak Brats

Homemade Pierogi

Ingredients

Dough

2 cups (240g) King Arthur Unbleached All-Purpose Flour
1/2 teaspoon salt
1 large egg
1/2 cup (113g) sour cream
4 tablespoons (57g) butter, room temperature

Filling

1 cup (227g) mashed potatoes, warm
1 cup (113g) sharp cheddar cheese, shredded

To finish

4 tablespoons (57g) butter, cold
2 large (156g) shallots, diced; or one medium (156g) onion, sliced