These are present at many family gatherings, not just christmas! My great grandmother used to make them all, but she never let anyone watch... so we've had to adapt it from several sources to get ones that closely match the ones she used to make! While you can put many different fillings inside these, the two most commonly at our table were potato and cabbage. Since I didn't like cabbage as a kid, these quickly became my favorite and the ones I enjoy making now. I tried to take some photos along the way to illustrate the process...
3c mashed potatoes (cook ~2lb yukon gold potatoes in well-salted water, drain **SAVE WATER** & mash)
10oz cottage cheese, drained
3 slices american cheese
1 onion, sauteed in butter
Mix all ingredients together. Can be prepared ahead and refrigerated until needed.
6c AP flour
1-2c potato water (saved from boiling the potatoes, see above)
2 eggs, beaten
Make a well in flour, add salt, eggs, and 1c water. Mix well to make soft dough, adding more water if needed. Knead until smooth and does not stick (you may need to add more flour). *Today I made another batch (made too many potatoes last time!) and did most of the dough mixing in the mixer with the dough hook. It worked well and contained the mess, so that was nice! I added some of the flour, salt, eggs, water, then added the rest of the flour a cup at a time. It came together and started pulling off the walls of the bowl. Then I took it out onto a floured surface and added some more flour until the dough was no longer sticky.* Cover with a dish towel and let sit a few minutes.
Clean the counter, line 2-3 baking sheets with wax or parchment paper, get a glass or cookie cutter (I think the glass I used was ~3" in diameter). Dust your working surface with flour, and get ready to roll :)
Cut dough ball in half, working with 1 half at a time. Keep dough that's not being used covered. Same goes for pierogies as you make them. Roll out dough on floured surface (i'd guess it was about 1/8-1/4" thick) and cut rounds with glass. Stretch out rounds a bit in your hands, and fill with ~1T filling (this will depend on the size you use). Seal edges and pinch with fingers for the scalloped edge, or press with the tines of a fork. (If you do different fillings, this is a good way to differentiate them) Place pierogies in a single layer on the prepared baking sheets.
You can do one of two things at this point, cook them immediately (7min in boiling salted water) or freeze them on the baking sheets. Since I was doing these by myself, I stuck them in the freezer, and a few hours later, repackaged them into freezer bags for safe keeping. When ready to eat, cook the frozen pierogies in boiling salted water for ~7min, or until they float. Drain and then toss with onions cooked in butter. Once you have these, you just can't have them any other way!!