Restaurants keep their mashed potatoes hot for 3 hours using warming drawers or insulated containers. Also, they use warming elements like adding boiling cream, gravy, or the combination thereof to make the potato heated over long hours.
Restaurants prepare the potatoes ahead by boiling and mashing just the potato, then just before serving, it is mixed into boiling cream (or milk or even broth or a combination thereof) to reheat it and make it nice and creamy.
There are two routes you can take: Probably the simplest is to place the mashed potatoes in a heat-proof bowl over a pot of simmering water. You can cover the bowl with foil, or use a lid that fits over the bowl. Make sure the water doesn't burn dry, and never gets above a simmer—and that's it.
"Hold your mashed potatoes in a bain-marie, or water bath, with a lid on top [and] they stay for hours — days really," Ray, who recently partnered with Home Chef, said in an interview with Allrecipes. The method is oh-so-simple. Just make your mashed potatoes according to your favorite recipe.
Mashed potatoes can sit out for two hours at room temperature. Any longer than that, they can enter the “danger zone,” which are unsafe temperatures that promote the growth of bacteria. If temperatures go above 90 °F, mashed potatoes can only sit out for one hour.
Leftover mashed potatoes are good for 3-5 days in the refrigerator and up to 12 months in the freezer. But, you'll need to make sure they're handled and stored properly. Starchy dishes like mashed potatoes grow microbes and create bacteria when left at room temperature for too long.
Make-ahead mashed potatoes are a great option for the holidays. You can do nearly everything — boil, peel, and mash; stir in milk and salt — up to two days ahead. Before serving, reheat. Adding butter at the last minute makes them taste freshly mashed.
Empty the cold mashed potatoes into a medium saucepan or Dutch oven and set over low heat. Cover the potatoes and stir them occasionally until they are completely warmed through and smooth. Be sure to keep the heat low and stir, otherwise the potatoes may start to stick to the bottom of the pan and scorch.
The best way to reheat mashed potatoes is to heat them covered in the oven at 350 degrees with extra milk and butter. Cook for 20 minutes or until warmed through. Don't worry if you don't have the time or means to heat your leftover potatoes in the oven.
— you may have wondered if you can shave off some party-day stress by making them ahead of time. We've got good news: You can prep the potatoes themselves a few days beforehand — and actually mash them up to 1 day before.
If you need to reheat mashed potatoes quickly, nothing beats the microwave. Put the potatoes in a microwave-safe dish, add a splash of liquid, and gently stir. Cover the potatoes with a lid to help preserve moisture, then heat at half power for 1 minute.
If you want to make potatoes a day ahead and reheat them.
You want them to just about drip off the end of a spoon. Put them in a deep casserole or soufflé dish — even a Dutch oven will do — and store in the fridge overnight. Warm them up in the oven the next day, uncovered, with a little butter on top.
Sour cream, butter, and Parmesan are all you need
The Barefoot Contessa places her mashed potatoes in a bowl over simmering water, and when heated through, she stirs in sour cream, Parmesan cheese, butter, salt, and pepper. These added flavors bring these already seasoned spuds to a new level of life.
If you'll be cooking the potatoes in the next few hours, you can leave them submerged in water at room temperature, Tiess says. If it will be longer than a few hours, place them in the refrigerator. Peeled, sliced, submerged, and refrigerated potatoes should be cooked within 24 hours.
A: If they were just mashed potatoes, they were probably ok to leave out. However, the issue is usually what was mixed into the mashed potatoes milk & butter can be a problem with dairy more so than olive oil or margarine.
Mashed potatoes can be kept warm in a crockpot (if serving later the same day) OR refrigerated for up to 2 days. To reheat, place them in a large pot over medium-low heat, stirring constantly and adding additional milk/cream as needed to achieve the desired consistency.
If stored correctly in plastic containers, leftover mashed potatoes can last 3 to 5 days in the fridge. Just make sure the leftovers are stored in a sealed container. An airtight container will keep the moisture inside the container and keep the potatoes from drying out.
If mashed potatoes cooked it will last from 3 to 4 days in the fridge and almost 10 to 12 months in the freezer depending on the kind of potatoes.
Your other option would be placing the prepared mashed potatoes in a buttered, oven-safe dish (covered in aluminum foil) and sliding it into a 275- to 300-degree oven. I wouldn't recommend trying to keep your spuds warm for more than 30-40 minutes using this method or you risk drying them out.
Serve warm: Potatoes are best if served soon after mashing them. However, you can also do this: Hold Potatoes on "Warm": Mashed potatoes can be held on the "warm" setting of your slow cooker for up to two hours or so without noticeable loss of flavor or texture.
Keep it on 'low' or 'warm'
The lowest setting of your slow cooker will keep the potatoes nice and warm without drying them out. If you notice that they are getting a little dry, loosen them up by stirring in an extra splash of milk or cream or a few tablespoons of butter.
Add an extra splash of cream or milk, and another pat of butter to ensure the mashed potatoes don't dry out. Stir them a few times until everything is warmed through (don't over stir or the mashed potatoes can assume a gummy texture!).
Add more cream and butter: More moisture and fat are the two secret ingredients to reheating any leftovers. For potatoes, reach for half-and-half or broth and butter. Cover and heat low and slow: Cover the baking dish and set it in a 350°F oven alongside any turkey leftovers you might be reheating too.