Pierogi Dough
2
cups full fat plain or Greek yogurt
1
egg, lightly beaten
1
teaspoon salt
2 1/4
cups flour + more for kneading

Potato, Mushroom & Caramelized Onion Pierogi Filling

2
yellow onions, chopped
1
pound white mushrooms, trimmed and finely diced
3/4
pounds potatoes for mashing
4 - 6
tablespoons unsalted butter
Salt and freshly ground black pepper
Sour cream or Full-fat or Greek yogurt for serving