There's a pizza joint here that makes a mashed potato pizza, using what I'm pretty sure are instant mashed potatoes as the sauce, topped with mozzarella, bacon, and scallions. It's good starchy food and I've had it in the back of my mind, minus the bacon, for Lent. I didn't use instant potatoes.
Colcannon pizza, because tomorrow is St Patrick's Day and because greens are good for you. I think colcannon is properly made with cabbage, but I used spinach because I had some on hand: I sauteed garlic and spinach in a little butter, added smoked mashed potatoes, and put that on a parbaked pizza crust with cheddar cheese and scallions.