I'm posting this so if I lose the yellowing piece of paper with the recipe, I won't be distraught. I can probably recite it from memory (testing...yes), but hey, the memory is the second thing to go.
2 cups of flour
1/2 cup sour cream
2 tablespoons of melted butter
3 egg yolks
Mix all ingredients until well blended and firm. Rest 10 minutes. Roll to 1/8 inch thickness and cut with round cutter (can from sauerkraut filling works very well). Recipe is supposed to yield 25 pieces, but aim for 30+. When rolling, take dough and split in half. Roll one half, cut, then reroll leftover dough one more time. Any more than that, and you'll get rubbery dough. Repeat with second half.
Filling...I really don't have a recipe. I do two: a sauerkraut and a cheesy potato. The sauerkraut contains sauerkraut and chopped mushrooms. Drain the kraut, saute the mushrooms, mix, and heat thoroughly, mostly to get a lot of the moisture out. For the potatoes, peel, quarter, and boil a bunch of potatoes (seriously, I go by feel on this), and grate a block of sharp cheddar cheese. Drain potatoes, add some milk and butter, and slowly add cheese while mashing. Make the filling the night before, and when you're beginning, remove from the fridge to bring it to room temp. Spoon into rounds, fold over, and seal with a fork.