How to Reheat Mashed Potatoes without Drying them Out

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Reheating mashed potatoes without turning them to glue or drying them out is difficult, but not impossible. Here are 4 proven methods for reheating them so they taste just as good as they did the first time around.

Anyone who’s ever cooked mashed potatoes knows how finicky this food can be. Cook the spuds too long and you end up with sticky mashed potatoes. Over mash the potatoes and everything turns to glue. Overheat your mash and you get a brown, crusty mess.

Given how difficult cooking fresh mashed potatoes is, it makes perfect sense that reheating leftover mashed potatoes would be a challenge. Luckily, there are some tried and true methods for reheating mashed spuds that deliver smooth, creamy potatoes without overdrying or turning them to glue.

So, what is the best way to reheat mashed potatoes? 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. There are three more methods that work almost as well that we will outline below, as well.

4 Ways to Reheat Mashed Potatoes

The reason mashed potatoes are so difficult to reheat has to do with their starch content. The amylose starch in potatoes reacts one of two ways when heated.

If exposed to dry heat, these starches turn brown and break down into sugar. This is what you see happening along the outer edges of a baked potato. This sweet crunchiness is great for campfire spuds, but not so desirable in mashed potatoes.

If exposed to moist heat, these starches absorb water, swell, and become viscous. The right amount of heat gives you smooth, creamy potatoes. But too much heat causes the starches to burst, and the potatoes to become gelatinous and gluey.

Fighting these two potential outcomes is difficult when you make fresh mashed potatoes, but it’s even more difficult when reheating leftovers. The four methods below were designed to keep your leftover potatoes moist while they reheat without allowing them to overheat.

1. In the Oven

The oven is the best choice for reheating mashed potatoes because you have very precise control over the temperature. You also can keep the potatoes covered to retain moisture so they don’t dry out.

But to keep your potatoes from turning to glue, you’ll also need to add extra liquid and oil.

The addition of salt and fat to mashed potatoes helps prevent the starches in them from absorbing too much water. When these starches can’t take in too much water, they can’t rupture, which means they won’t turn to glue, even under high temperatures. For this reason, you should always add extra butter or oil and some sodium to your leftover mashed potatoes before heating.

Adding additional liquid, such as milk, plant-based milk, or vegetable broth can also help by keeping the potatoes from drying out.

To reheat mashed potatoes in the oven:

  1. Place your leftover mashed potatoes in an oven-safe dish.
  2. Stir in melted butter, melted vegan butter, or oil and milk/cream, vegan milk, or broth. Start with about 1/2c liquid for every 4 cups of potatoes. Your final product should be smooth but not runny.
  3. Cover the dish with a lid or foil and place in an oven preheated to 350 degrees.
  4. Cook for 20 to 30 minutes or until heated through (at least 165 degrees).

This method allows your potatoes to heat gradually while retaining moisture and avoiding gelatinization. It takes a little longer than other methods, but produces the most consistent results.

2. In the Slow Cooker

Another great method for reheating mashed potatoes is in the slow cooker. 

Like the oven, the slow cooker allows the potatoes to retain moisture and to heat gradually. You don’t have quite as much control over the temperature. But as long as you’re patient, it is difficult to overheat potatoes this way.

To reheat mashed potatoes in a slow cooker:

  1. Coat the slow cooker insert with butter, vegan butter, or oil.
  2. Add a small amount of liquid (cream/milk, vegan milk, or broth) to the bottom of the pot.
  3. Stir butter, vegan butter, or oil and milk/cream, vegan milk, or broth into your mashed potatoes before adding them to the pot. Start with about 1/2c liquid for every 4 cups of potatoes. Your final product should be smooth but not runny.
  4. Add the potatoes to the slow cooker, cover, and cook on low until the potatoes are heated through. Continue to warm in the pot for up to 4 hours.

This method takes the longest but works very well if you have premade your mashed potatoes to serve alongside a larger meal. If you have a lot of food prep to do for Thanksgiving dinner, for instance, making your potatoes early and reheating them this way is a great way to reduce your workload and save oven space.

3. In a Double Boiler

Using a double boiler allows you to reheat mashed potatoes relatively quickly without risking drying them out. If you don’t have a true double boiler, you can DIY your own by placing a heat-proof glass bowl on top of a pot filled with water.

Just make sure the top edge of the bowl is wide enough to sit above the boiling water and that you have a lid that fits tightly over it.

To reheat mashed potatoes in a double boiler:

  1. Add the mashed potatoes to the top of the double boiler or to your glass bowl.
  2. Stir in melted butter, melted vegan butter, or oil and milk/cream, vegan milk, or broth. Start with about 1/2c liquid for every 4 cups of potatoes. Your final product should be smooth but not runny.
  3. Fill the bottom pot with water. Make sure the water is below the bottom of the top bowl.
  4. Boil the water with the lid secured over the potatoes. Stir frequently but not vigorously until the potatoes are heated through.

This method is quicker than the previous two but runs a higher risk of overheating the mashed potatoes, especially if you are not stirring frequently enough. However, the added moisture and indirect heat from the boiling water will help prevent the potatoes from drying out.

4. In the Microwave

The microwave is by far the quickest method for reheating mashed potatoes, but it is also the trickiest method to get right. Too much heat and you’ll dry your potatoes out. Too much moisture and they’ll turn to glue.

The directions below work well in most situations but will need to be adapted based on your microwave power and how much mashed potatoes you’re reheating at once.

To reheat mashed potatoes in the microwave:

  1. Place your potatoes in a microwave-safe bowl.
  2. Stir in melted butter, melted vegan butter, or oil and milk/cream, vegan milk, or broth. Start with about 1/2c liquid for every 4 cups of potatoes. Your final product should be smooth but not runny.
  3. Cover and microwave on 50% power for 1 minute.
  4. Stir gently and place back in the microwave for another minute.
  5. Continue stirring and heating like this until the potatoes are heated through.

If you notice your potatoes getting too dry, add more liquid. If they are getting gummy, turn the power down even more and stir less frequently.

How to Store Leftover Mashed Potatoes

The best way to store leftover mashed potatoes is in an oven-safe dish with a tight-fitting lid placed in the fridge. This way, when you are ready to reheat your potatoes, you only have to stir in your extra oil and liquid and pop them in the oven.

If you plan to reheat a small amount at a time, portion the mashed potatoes out into individual servings and store them in airtight containers in the fridge. 

How Long are Leftover Mashed Potatoes Good For?

Like most leftovers, mashed potatoes are good for around 3 to 5 days when stored in an airtight container in the fridge. Potatoes without dairy ingredients may last slightly longer.

When reheating your mashed potatoes, be sure to get the internal temperature up to 165 degrees before enjoying.

Mashed potatoes in a cast iron crock on a wooden table

The Best Way to Reheat Mashed Potatoes

Reheating mashed potatoes without turning them to glue or drying them out is difficult, but not impossible. Here's the best way to reheat mashed potatoes so they taste just as good as they did the first time around.
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5 from 2 votes
Print Pin Recipe
Course: Side Dish
Keyword: reheat mashed potatoes
Cook Time: 20 minutes
Total Time: 20 minutes
Author: Sara Seitz

Ingredients

  • 1 batch leftover mashed potatoes

Instructions

  • Place leftover mashed potatoes in an oven-safe dish.
  • Stir in melted butter, melted vegan butter, or oil and milk/cream, vegan milk, or broth. Start with about 1/2c liquid for every 4 cups of potatoes. Your final product should be smooth but not runny.
  • Cover the dish with a lid or foil and place in an oven preheated to 350 degrees.
  • Cook for 20 to 30 minutes or until heated through (at least 165 degrees).
Tried this recipe?Mention @CleanGreenSimple or tag #CleanGreenSimple!
Sara Seitz

About the Author

Sara Seitz is a freelance writer living with type 1 diabetes. Her search for better health and better control of her blood sugars led her to a plant-based diet. When she isn’t experimenting with new vegan recipes, she’s helping spread the word about how plant-based is better for people and the planet. More articles by Sara.