Not something we had ever come across until we moved to Canada, but very much a favorite over here.
We keep bags of frozen perogies ready to be used. Easy to take out the required quantity. These are surprisingly filling little blighters. I reckon on serving only 6 to 8 per person, so you do need to count them out or you can easily over-cater.
Cook the perogies according to instructions - basically boiling for about 10 minutes.
Serve topped with sour cream, grated cheese, fried bacon, and chopped chives and spring onions.