How to Thicken Mashed Potatoes: 3 Foolproof Ways

Nobody likes runny mashed potatoes! Here's a handful of ways to fix those mashed potatoes into spuds good enough that people will ask for seconds.

Perfect Mashed Potatoes

Never fret over a batch of “ruined” mashed potatoes again. Here’s everything you need to know about thickening runny potatoes.

Why Are My Mashed Potatoes Runny?

There are quite a few reasons your mashed potatoes are watery. If you’re staring down at a bowl of white liquid and wondering what went wrong, ask yourself these questions:

  • Did I use soggy potatoes? It’s essential to drain and dry your potatoes well after you’ve cooked them in water. If you don’t, all that excess moisture will have nowhere to go once you start mashing.
  • Did I cook my potatoes too long?: Overcooked potatoes can be waterlogged.
  • Did I use too much liquid? This is an obvious issue. Make sure to read your recipe well and use the proper ratio of milk or cream to potatoes.

No matter how they happened, there are a few simple ways to fix your runny potatoes.

Add Dehydrated Potatoes

That’s right—you can thicken potatoes with potatoes! It's the easiest and fastest way, as long as you have them on hand. Here's the method recommended by Dr. Potato at the Idaho Potato Commission: An “easy fix for watery potatoes is to break out the instant dehydrated potatoes and mix them in a tablespoon at a time, into the wet potatoes. This usually will thicken them up.”

Add a Thickening Agent

This is the most common way to thicken mashed potatoes. You can use what you have on hand: Flour, cornstarch, or powdered milk are all solid options that are probably already in your pantry. Potato flour and potato starch would work as well.

Stir in the thickening agent gradually, about a tablespoon at a time, until the potatoes have reached your desired consistency. Be conservative, as too much thickener can lead to gluey mashed potatoes.

Reduce Them Over Heat

You can also thicken your mashed potatoes by continuing to cook them on the stove with the lid off. Heat draws the excess moisture out of runny potatoes, leaving you with a denser finished product.

This is a risky move, though, as overdone mashed potatoes are gummy and unpleasant. Make sure to keep a close eye on them if this is the method you choose.

As they cook, stir every so often so they don’t stick to the bottom of the pot. But don’t stir too much! Overworking is another way to ruin the potatoes’ texture.

If your stove is full, you can use the oven to accomplish the same thing. Just place the potatoes in an uncovered, oven-safe casserole dish and heat them for about 10 minutes at 325 degrees F.

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