Leftover mashed potatoes are a hard sell the next day: they reheat stiff and gluey, and nobody gets excited about them. But those same potatoes are nearly perfect raw material for something better. Shaped into patties and pan-fried, they come out crisp and golden outside and soft and creamy inside, which makes this the recipe to make the day after a roast dinner or holiday meal, when a bowl of leftover mash is taking up fridge space.

Cold is the whole trick. Chilled mashed potatoes are firm and hold their shape in the pan, while warm ones spread out and fall apart when you try to flip them. The egg and a little flour bind the mixture, the cheddar melts in and browns into a crisp lacy crust, and the green onions keep the flavor from reading as one-note starchy.

Each pancake has a crunchy browned exterior that gives way to a soft center, like a cross between a latke and a loaded baked potato. Eight pancakes feed four as a side dish or two as a light main. They are good plain, but sour cream and a squeeze of lemon or a few dashes of hot sauce turn them into dinner.