Some leftovers, like soups and stews, are even better the next day; that extra time in the refrigerator allows their flavors to marinate and develop. Other leftovers, however, like the holiday side dish staple mashed potatoes, are best enjoyed hot and fresh the day they’re made. This is because a lot of what makes mashed potatoes delicious — their creaminess and silky smooth texture — don’t keep well in the refrigerator. 

As mashed potatoes sit in the fridge, their starches solidify and can become gummy or gluey. Also, the butter, milk, or cream is prone to separate, and the dish as a whole is likely to dry out because refrigerators are dry environments. You might be able to salvage them the next day by heating them up with additional butter or cream, but they’ll probably never return to their former glory. Instead, here are a few creative ways to use up leftover mashed potatoes that won’t leave you wishing it was yesterday. 

5 creative ideas for leftover mashed potatoes

In an ideal world, you’d only be making as much food as you can eat, as to not waste anything.    This isn’t always possible — especially around the holidays. Here are give ways to make the most of your leftover food. 

Make mashed potato pancakes

Spencer Scott and Nick Schwanz, founders of Solar Punk Farms, a climate education farm in Guerneville, CA, do whatever they can to keep leftovers out of the landfill. 

“The first and best thing you should do with leftover mashed potatoes is eat them,” they say. “We love to keep the feast going the next morning and make potato pancakes or latkes. And if there are still leftovers, we remind ourselves to make less next year and then feed the rest to our chickens or worms in our vermicompost bin (who turn it into fertilizer for the farm!).”

Here’s an easy recipe for mashed potato pancakes you can enjoy the next day. 

Ingredients

• 2 cups leftover mashed potatoes 

• 1 large egg

• ½ cup all-purpose flour 

• ½ cup shredded cheddar cheese (optional) 

• ½ cup chopped green onions (optional) 

• Salt and pepper to taste

To make mashed potato pancakes, simply combine all the ingredients in a large bowl and mix well. If you want to take them up a notch, throw in some grated cheese or scallions. Then, melt two tablespoons of butter in a skillet over medium heat. Once the butter is melted and the pan is hot, use your hands to form the mashed potato mixture into six to eight evenly sized potato patties, depending on how large you want them. Gently lay them in the pan and fry for three to five minutes per side, or until each is warmed through and golden brown. You may need to fry them in a few batches depending on the size of your pan. 

Serve them with leftover gravy as syrup and garnish with more shredded cheese or chopped green onions. 

Make mashed potato waffles

If you’ve got a waffle iron on hand, you can make mashed potato waffles. This one’s easy: All you need to do is make a batter using the recipe for mashed potato pancakes, but instead of forming them into patties, simply drop evenly-sized balls into the center of a greased waffle iron and then cook until they are golden brown. 

You can serve them with gravy “syrup” or create a waffle bar with lots of toppings, like sour cream, green onions, smoked salmon, dill — anything you’d want to enjoy on top of some crispy potato goodness. 

Make potato dumplings

Potato dumplings are wonderful additions to something like a leftover soup, which uses several holiday leftovers in one dish. They are a great way to use up mashed potatoes and give them new life. Potato dumplings aren’t wrapped like many Asian dumplings but are doughy dumplings similar to matzo balls or drop dumplings. 

Ingredients

• 1 cup leftover mashed potatoes 

• 1 large egg

• ½ cup all-purpose flour 

• ¼ cup parmesan cheese (optional) 

• ¼ chopped herbs, like chives or parsley (optional)

• Salt and pepper to taste

To make potato dumplings,  mix all the ingredients in a large bowl until a dough forms. You should be able to roll the dough in your hands without it sticking. If it does stick, add a bit more flour. Next, shape the dough into ping-pong ball-sized rounds and set them on a tray. Carefully drop the balls into gently simmering broth or soup and let them cook for five to seven minutes. 

And that’s it! Serve, garnish, and enjoy these little fluffy potato pillows. 

Pipe onto shepherd's pie 

Leftover mashed potatoes make a great topping for a shepherd's pie. All you’ll need to do is fill a casserole dish with your favorite shepherd’s pie filling, spread the mashed potatoes over the top, and bake until they are warmed through and golden brown on top. 

If you want to get a little fancy with it, fill a large ziplock bag with your mashed potatoes, seal it, and then cut one corner of the bag off to pipe the mashed potatoes on top in an elegant pattern. 

For a holiday spin on the classic shepherd’s pie, consider this: Combine leftovers like turkey, vegetables, and gravy in a casserole dish and top them the same way with mashed potatoes. Voila — you’ve just created a custom leftover pie for a tasty meal that’ll help you prevent food waste. 

Thicken soup 

If you really don’t want to do any more work with your mashed potatoes, you can whisk them into broths or soups as a thickener to create some creamy deliciousness. The starch in potatoes is a natural thickener, so whisking in a cup of leftover mashed potatoes to any soup or broth will help give it a silky, thick texture and, depending on what you made your mashed potatoes with, lend some creamy, buttery flavor as well. 

How long do leftover mashed potatoes last?

If you don’t feel like cooking the day after a big meal, we don’t blame you. Still, you should plan to use your leftover mashed potatoes within three to four days if you stored them in the refrigerator. While they can be frozen indefinitely, it’s recommended to eat frozen leftover mashed potatoes within one to two months to ensure freshness. 

For maximum freshness, store leftover mashed potatoes in an airtight container. Otherwise, they might oxidize and turn gray — it shouldn’t impact the flavor, but let’s be honest, no one wants to eat gray potatoes. 

If you aren’t able to make use of your leftover mashed potatoes, and you don’t have any backyard chickens to feed them to, you can recycle them with Mill. The Mill food recycler will turn mashed potatoes, along with all your other uneaten food and kitchen scraps, into Food Grounds that can be used as nutrient-rich soil amendment or added to your compost pile.

Sources:

1. U.S. Department of Agriculture: “How long can you store cooked potatoes?” September 18, 2024, https://ask.usda.gov/s/article/How-long-can-you-store-cooked-potatoes

2. U.S. Department of Agriculture, Food Safety and Inspection Service: “Freezing and Food Safety.” August 9, 2024. https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/freezing-and-food-safety

3. Foodsafety.gov: “FoodKeeper App.” April 26, 2019. https://www.foodsafety.gov/keep-food-safe/foodkeeper-app

4. The Idaho Potato Commission: “How Long Can Mashed Potatoes be Safely Refrigerated?” https://idahopotato.com/dr-potato/how-long-can-mashed-potatoes-be-safely-regrigerated