sure- make changes as you like. I know prune pierogi are popular around here, but I don't know if I could eat them. This is a starter recipe- you can make variations. I agree, the butter is what makes them. Let me know how your saurkraut ones turn out.
Oh I also make an "Easy Piggies" recipe where you shred the cabbage, layer on the bottom of the casserole pan, mix the ground beef, eggs and rice together, layer over the cabbage, pour the tomato soup over the top, cover and bake. I like this since I don't have to fiddle with the leaves. And they also call piggies- pigs in the blanket.
Enjoy!