The first flip is the moment I watch most closely: a good potato cake should lift with a browned, crisp underside, not slump when the spatula slides beneath it. These leftover mashed potato cakes give cold potatoes a second life, with sharp cheddar and scallions mixed right into the centers. The outside browns in the skillet while the middle heats through, so I keep the patties about half an inch thick instead of shaping them into thick, heavy rounds.
Cold mash is easier to shape than warm mash, and the flour and egg bind the mixture without a separate coating. Fold everything together until the cheese and scallions are spread throughout, then shape all eight patties before you start frying. Cooking four at a time gives each cake room in the skillet and keeps the batches manageable. The finished cakes have crisp golden edges and a tender potato center.
Kitchen Note
I don’t press the patties down once they hit the pan. They’re already thin enough to cook through, and leaving them intact helps them hold their shape as the crust forms.
Save these leftover mashed potato cakes for a crisp-edged way to use up cold mashed potatoes, cheddar, and scallions.
Why the Skillet Gets Only Four Potato Cakes at a Time
It’s easy to look at eight small patties and think they’ll all fit in one go. In a 12-inch skillet, frying four at a time gives you room to move a spatula between them and turn each cake without bumping its neighbor. That matters with a mixture that’s soft before its crust sets. Crowding the pan also makes it harder to keep the cakes in contact with the hot skillet, which can leave the undersides pale instead of crisp.
The two-batch setup has another practical benefit: you can give the first four your attention while they cook, then add fresh oil for the next round. Keep the heat at medium rather than turning it up to hurry the browning. If the pan is too crowded or too hot, the outside can brown unevenly before the potato mixture has had time to heat through. Let each batch cook undisturbed until it’s ready to turn, and the cakes are easier to handle from skillet to plate.
Cold Potatoes, Egg, and Flour Build the Cake; Cheddar Brings the Bite
- Cold mashed potatoes — These are the base, and their texture depends on how the original mash was made. Cold potatoes are firm enough to shape; very loose mashed potatoes make softer patties, so shape them gently and keep them at the stated thickness.
- Egg and all-purpose flour — Together, they help hold the potatoes in patties as they fry. The egg binds the mixture, while the flour is mixed through it rather than used as an outside coating. I wouldn’t leave either out; without that structure, the cakes are more likely to fall apart.
- Sharp cheddar — Its tang stands up to the mild potatoes and melts into little pockets throughout each cake. Freshly shredded cheddar gives you control over the shred size, while pre-shredded cheddar is convenient and works here, too.
- Scallions — Thin slices distribute more evenly than large pieces, so you get a little onion flavor throughout instead of one strong bite. Their fresh, mild flavor balances the richness of the cheese.
- Vegetable oil — This is the frying fat for both batches. Measure it into the skillet in two portions as you cook; the second addition gives the remaining cakes fresh oil for their turn in the pan.
From Cold Mash to a Crisp, 165°F Center
Mix the potatoes and binder first
Stir the cold mashed potatoes and egg together in a medium bowl. Fold in the flour, cheddar, thinly sliced scallions, salt, and pepper until the mixture is evenly combined. Scrape the bottom of the bowl as you fold so there aren’t pockets of flour left behind. Stop once the ingredients are distributed; you don’t need to mash the potatoes smooth.
Shape eight even patties
Divide the mixture into eight patties, each about half an inch thick. Similar thickness helps the cakes cook at the same pace, so take a moment to even out any noticeably thick spots. The mixture will feel soft, but the cakes should hold together when you lift them. Set all eight aside before heating the skillet so you can focus on the frying.
Brown the first four
Heat two tablespoons of vegetable oil in a 12-inch skillet over medium heat. Add four patties and fry them for 4–5 minutes per side, turning when the first side is golden brown and crisp. The centers must reach 165°F; check in the middle of a cake rather than judging by the crust alone. Transfer the cooked patties to a paper towel-lined plate.
Fry the second batch
Add the remaining two tablespoons of oil to the skillet, then cook the remaining four patties the same way. Keep the heat at medium and give both sides time to turn golden and crisp. Move the finished cakes to the paper towel-lined plate. If the skillet looks crowded, don’t squeeze the patties together; their edges need room for your spatula.
Ways to Adjust the Cakes Without Losing Their Shape
Make a dairy-free batch
Leave out the cheddar and use mashed potatoes that are themselves dairy-free. The egg and flour still bind the patties, though the cakes will have less richness and no melted cheese pockets.
Skip the scallions for a milder cake
Leave out the scallions if you want the potato and cheddar to come through on their own. The mixture will still hold together; the cakes simply lose that fresh, oniony bite.
Fry a half batch
Halve each ingredient to make four cakes. Beat the egg first, then use half; shape the patties to the same thickness and fry them in batches as needed. This is handy when you have less leftover mash and don’t want extra cakes on hand.
Storage and Reheating
- Refrigerator: Store cooked cakes in an airtight container for 3–4 days. The crust will soften in the fridge.
- Freezer: Freeze the cooled cakes in a single layer, then transfer them to a freezer-safe airtight container. They keep well for about 2 months; thaw in the refrigerator before reheating.
- Reheating: Warm them in a skillet over medium heat until heated through, turning once. The microwave is quicker, but it softens the crisp edges.
Questions That Come Up When Frying Potato Cakes
Leftover Mashed Potato Cakes
Ingredients
Equipment
Method
- In a medium bowl, stir together the cold leftover mashed potatoes and egg, then fold in the flour, shredded sharp cheddar, thinly sliced scallions, kosher salt, and black pepper until evenly combined.
- Shape the mixture into 8 patties about 1/2 inch thick.
- Heat 2 tablespoons of the vegetable oil in a 12-inch skillet over medium heat.
- Fry 4 patties for 4–5 minutes per side, until golden brown, crisp, and heated to 165°F in the center.
- Transfer the patties to a paper towel-lined plate.
- Add the remaining 2 tablespoons oil to the skillet.
- Fry the remaining patties the same way, for 4–5 minutes per side, until golden brown, crisp, and heated to 165°F in the center.