Mashed potatoes on a pizza? You don't say! Pierogies are a pretty big deal here in Pittsburgh. We even have pierogi races at PNC Park. I love pierogies.
I have a theory that you can tuck almost any finely chopped or shredded vegetable into a savory pancake, fry it in small mounds until crisp on both sides, serve it with a dollop of a sour cream or yogurt sauce and they will be inhaled.