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.
"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.
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.
Instead, seal your fully made mashed potatoes—cream and all—in a vacuum bag, and keep them warm using an immersion circulator until ready to serve. At this point, immersion circulators are affordable enough to make them a viable option for many home cooks.
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.
If you refrigerated your mashed potatoes in an oven-safe casserole dish, set them out on the counter to take the chill off for at least 20 minutes before you pop them into the oven. When you're ready, bake, covered, at 350 degrees for 15 to 20 minutes, or until the potatoes are hot throughout.
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.
These mashed potatoes work well for any holiday dinner or lunch, for Thanksgiving, or just a side dish for a regular family meal. You can make them up to 3 days ahead and simply warm up to serve. They're so good and taste exactly the same when reheated, which is amazing.
The ideal temperature to keep mash potatoes warm is 300 degrees Fahrenheit, especially when you're using an oven or crock pot. But, to keep it warm without overcooking, make sure to put it in a pan or bowl covered with foil before placing it inside the oven. What is this?
Take your mashed potatoes out of the fridge and set them on the counter for about 20 minutes to bring them to room temperature. Meanwhile, preheat the oven to 350°F. Then, pop them in the oven, covered, for about 15-20 minutes, or until warmed through.
Whether reheating leftovers or using a recipe to make mashed potatoes ahead of time for a crowd, warming those spuds in a double boiler will do the trick. Alternatively, you can place your potatoes in a Pyrex glass bowl set over (but not in) simmering water.
Fresh mashed Idaho® potatoes should be held for no more than 60 minutes on a steam table (moist heat #7) or warming cabinet (175 °F – 200°F). Always preheat the steam table or warming cabinet. Keep potatoes covered with a layer of plastic wrap or a lid. If dry heat is used, set a pan in water bath.
To Keep Mashed Potatoes Warm All Day…
You can either make them in the Crock-Pot and leave them in it on low heat, or you can add them to the slow cooker after preparing them on the stove. Just be sure to grease the insert with butter or cooking spray first to keep the potatoes from sticking.
Spoon the potatoes into the serving dish, if you are serving the dish family style. Use the back of the spoon to smooth and round the pile of potatoes. If you are plating the potatoes in the kitchen, leave them in the mixing bowl or pot and cover the bowl with aluminum foil until you are ready to serve.
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.
To reheat mashed potatoes in the oven:
Add a bit of butter, milk, or cream for extra moisture. Cover the dish with foil and bake for 10-15 minutes, stirring gently every 5 minutes. Once your bowl of potatoes is hot, at least 165°, you can serve and eat.
Reheating mashed potatoes in a slow cooker or Crockpot ⇢ Making use of a slow cooker or Crockpot is a great option if you're low on oven space on Thanksgiving Day! Transfer the potatoes to your slow cooker & reheat with the low setting for 3-4 hours.
Test Kitchen Tip: You can boil potatoes ahead of time for use later as long as you cover and refrigerate them. They'll last for up to three days in the fridge.
The whole process is simple: peel them, leave them whole or dice them if you want, fill a bowl with cold water, submerge the potatoes and store in the fridge overnight. While this trick can be quite handy, it will only work for about 24 hours, so we would recommend to not prep your potatoes too far in advance.
Reheat a Baked Potato in the Oven
Preheat the oven to 350°F and take the potatoes out of the fridge to reach room temperature. Place the potato on a baking sheet or directly on the oven rack to achieve a crispy skin—Bake for 15 to 20 minutes or until the potato is thoroughly heated.
We've made mashed potatoes the day before Thanksgiving and re-warmed them with great success. Add a healthy extra dose of cream and butter, so that the potatoes are almost soupy. You want them to just about drip off the end of a spoon.
Prepping the potatoes ahead of time
To save time on peeling and chopping on Thanksgiving Day (or any other day that includes mashed potatoes), you can peel the spuds and keep them submerged in a bowl of water in the fridge, whole or cut up, for hours — even overnight — before boiling.
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.
If food has been hygienically prepared, cooled quickly after cooking (or reheating) and stored cold, reheating more than once should not increase the risk of illness.