We have a local place that has a mashed potato pizza. That's what my wife ordered on our first date.A local pizza place does what they call Potato Pie - it's a "white" pizza with no sauce, just olive oil, oregano and parmesan rubbed on the crust, followed by a layer of thinly-sliced potatoes (almost potato chip thin), then covered with mozzarella cheese and crumbled bacon on top.
I usually have them put onions on mine
She's still very fond of it (and me, luckily).