Mashed potatoes are about as versatile a side dish as you could ask for. They go with almost anything and they're inexpensive and easy to make. But best of all, you can save mess and fuss by prepping them ahead of time and reheating them when you're ready to eat them. There are lots of different ways to reheat your mashed, depending how much time you have and how many you're feeding.
Every Situation is Different
It's impossible to say one method is "best" for reheating mashed potatoes because every situation is different. The best way of heating up a few tablespoons of spuds won't necessarily work well if you're heating up potatoes for 200 at a holiday buffet. There's also the question of what equipment you have at your disposal, and whether it's already in use for other parts of the meal. The best way to reheat mashed potatoes, in short, is the way that works best for you right here, right now.
Reheating Mashed Potatoes in a Microwave
The fastest way to warm up your mashed potatoes is in the microwave, and it works pretty well for small portions. If you're heating up a single serving, you can just spoon it onto your plate and give them 30 seconds on high. Mash the potatoes around with your fork to distribute the heat evenly, then add a dab of butter or a few drops of cream if you wish. Pop them back into the microwave and zap them for an additional 10 seconds at a time until they're heated all the way through.
If you're warming potatoes for 2 to 4 people, use a microwave-safe dish with a cover. Give them five minutes or so at half power, stirring at least once to redistribute the heat. Once they're finished, stir in a bit more milk and cream, and taste them to make sure they're hot all the way through. If not, put them back and give them another 20 to 30 seconds at a time until they're fully heated.
Reheating Mashed Potatoes In the Oven
Your oven is another useful place to reheat mashed potatoes. One of its biggest virtues is that you can do almost any quantity of potatoes, from the largest to the smallest. If you're doing a relatively small portion of potatoes, enough for 2 to 8 people, your best bet is simply to put them into a baking dish with a lid and slide them into the oven along with any other dishes you're preparing. Add a splash of milk, cream or broth to keep the spuds from drying out, and a dab of butter for richness.
At the same 350 degrees Fahrenheit you'd use for most other cooking, your potatoes should take 30 to 40 minutes to heat all the way through. They'll need to be stirred once or twice, to keep them from sticking or scorching on the sides of the baking dish. You can use a higher or lower temperature if your oven is set to that level for other dishes, and adjust the reheating time as needed.
Reheating a large quantity of mashed works pretty much the same way, except you'll need a larger pan and you might not be able to fit anything else in your oven. A large roasting pan with a lid, or a disposable foil pan with foil folded over the top to close them in, are your best bets. Depending on the size of your pan, you may need to start warming them an hour or two before mealtime.
Reheat Mashed Potatoes In Your Crock-Pot
If you have a lot of potatoes to reheat, but your oven is tied up with other things, consider warming them in your slow cooker. A 6- or 7-quart Crock-Pot can easily hold up to 10 pounds of potatoes, which is plenty for 20 people. You'll need to start heating your potatoes at least three hours in advance and possibly more. It's best to start early because if need be, your slow cooker is also a great place to keep your potatoes warm until it's time to serve them.
Reheating Mashed Potatoes Sous Vide
In some ways, sous vide might be the best of all reheating methods for mashed potatoes. A sous vide controller is a device that looks a bit like a stick blender. It keeps a pot or tub of water at a very precise temperature and circulates it, so you can warm your spuds to the exact temperature you want without them getting dried out or scorched. Just portion your potatoes into vacuum-seal or zipper-seal bags, then drop them into the water bath at 150 or 155 F for an hour to reheat. You can hold them at that temperature for up to a day without any appreciable loss of quality.