I used my own mashed potatos, with more cheddar and sour cream, and cottage cheese. Boiled the potatoes with crushed garlic cloves that i mashed up with the potatoes. Had way too much potato filling, wound up making Italian Mashed Potato Pie with the leftovers. This dough made 48 pierogies, and it took me 5 1/2 hours when all was said and done, though I was taking my time. my boyfriend, who's Polish was happy as a clam, and managed to groan delightedly a few times in between bites lol! Served with two diced onions sauteed in butter, used 3 sticks of butter total and a basting brush to keep them all well coated. Not sure how often I'll be making these, bet they are a great treat!
This is a great Pierogi recipe, I've been using it for years and find it easier to stretch the dough than in the other ones I tried before it. I recommend it...though the ingredient list may seem long it really is worth the effort...makes an enormous batch as well.