How to Thicken Mashed Potatoes

Co-authored by Isabelle Garson

Mashed potatoes are a classic comfort food dish. However, it can be pretty disappointing if they turn out too watery or runny. This can be a result of overcooking the potatoes, adding too much milk, or not draining all the cooking water. Fortunately, there are several ways you can achieve that perfect consistency, including using heat, flour, thickening agents, or more potatoes.

Method 1

Method 1 of 3:

Using Heat to Thicken

1
Heat the potatoes on the stove, stirring occasionally. Place the potatoes in a large uncovered pot over medium-low heat. Stir occasionally with a fork until the extra moisture evaporates and the potatoes achieve the consistency that you want.
- Stirring will prevent the potatoes from clinging to the bottom of the pan, but don’t stir constantly! This will overwork the potatoes and give them a gummy, overly-starchy texture.^{[1]
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2
Microwave the potatoes in a bowl for 1-2 minutes. Put the potatoes in a microwave-safe bowl and leave it uncovered. After each minute, take the bowl out of the microwave and check the consistency. Keep warming it in increments of 1 minute until the potatoes have thickened to your liking.^{[2]
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- Set your microwave on high.
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3
Bake the mashed potatoes at 325°F (163°C) for 10-15 minutes. Preheat your oven to 325°F (163°C) and place your runny mashed potatoes in a glass casserole dish. Once your oven has preheated, bake your potatoes for 10-15 minutes to dry the moisture out of them.^{[3]
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- Leave the casserole dish uncovered while you bake it.

Method 2

Method 2 of 3:

Adding Thickening Agents

1
Choose a thickening agent that works for you. There are several ingredients that you can add to your potatoes that will quickly thicken them. They include flour, cornstarch, powdered milk, instant potato flakes, potato starch, arrowroot, tapioca, or parmesan cheese.
- Cornstarch is gluten-free, and also has twice the thickening power of flour.^{[4]
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  Research source} Therefore, you probably will not need to use as much of it.
- Potato starch is another gluten-free option. Additionally, it’s the best starch for Passover cooking.^{[5]
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2
Stir in 1 tablespoon (7.81 grams) of your chosen thickening agent. Stir in the thickening agent with a fork until the agent is thoroughly incorporated into the potato mash. You may not notice a big difference in the consistency immediately — that’s okay!
3
Continue adding the thickener 1 tablespoon (14.8 ml) (7.81 grams) at a time. Stir after every addition. Do this until you get the thicker consistency that you want.^{[6]
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Method 3

Method 3 of 3:

Thickening with More Potatoes

1
Shred 1-2 raw potatoes into a medium-sized skillet. Use a cheese grater to do this. The potatoes should look like hash browns. This might take a while, but it’s important that they are finely shredded so they’re not too chunky when you incorporate them into your mash.
- Your cheese grater may have multiple sides. The medium-sized holes (not the largest and not the smallest) are the most suitable for shredding potatoes into hash browns.^{[7]
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2
Add enough water to cover them, and then bring the mixture to a boil. The amount of water that you need to add will depend on the size of your skillet, but the rule of thumb is that the potato shreds should just barely be submerged in water. Then, bring the mixture to a boil over medium heat.
- Leave the pot uncovered on the stove.
3
Drain the water once the potatoes are soft. Check the tenderness of the potatoes as soon as the mixture comes to a boil by sampling one with a fork. If they are soft and tender, quickly drain the water using a colander.
- If the potatoes are not yet soft and tender, leave them on the stove and check them after each minute that they continue cooking. Potatoes tend to cook quickly, so it’s important to check them often!
4
Mash the potato shreds with a fork. Transfer the potatoes back into the skillet, and use a large fork to mash them to your desired consistency. Beware of over-mashing them, as this won’t be very helpful when you go to add them to your existing watery mashed potatoes.
5
Mix the freshly-mashed potatoes with the watery mashed potatoes. Use a spoon to incorporate them fully into your existing watery potato mash. This should thicken them considerably.
- If they aren’t thickened to your liking, repeat this process and add more potatoes!