Mashed Potato Soup is a great way to use up leftover mashed potatoes. This quick cooking soup comes together in 30 minutes with just 6 ingredients. Even better, your family will never know they are eating the leftover mashed potatoes!
So the leftovers are dwindling? You have random bits and pieces of your holiday dinner scattered throughout your refrigerator? Did you make one too many potatoes this year? All you need is 3 cups of leftover mashed potatoes to make the most decadent mashed potato soup I’ve ever tasted. I mean this soup is rich, creamy, and full of flavor with only a few ingredients!
My goal after the holidays is to use up and re-purpose all my leftovers. I love to transform leftovers into brand new meals. This ensures that everyone in my house doesn’t get tired of eating a ham dinner for the 15th time in just 3 days. I almost always make over 10 lbs of potatoes for Thanksgiving. Even if it’s only 8 of us! That meant that everyone had to eat over a pound of mashed potatoes and we would still have leftovers.
The day after any holiday (or really whenever I have leftover mashed potatoes) I always make my easy mashed potato cakes. I also have tried my friend Joanne’s recipe for Crispy Mashed Potato Mounds which were out of this world delicious.
But even after that I still had about 3 cups of leftover mashed potatoes. That is when the thoughts of baked potato soup crossed my mind. Well, I should say, Mashed Potato Soup. With or without the bacon, this recipe for leftover mashed potato soup is out of this world delicious! Go ahead, give it a try and use up the last of your leftover mashed potatoes.
Ingredients
- Leftover Mashed Potatoes – You need at least 3 cups to make this recipe. You can easily add more mashed potatoes for a thicker soup. If your potatoes are chunky you will have a chunkier potato soup. If the mashed potatoes are smooth you will have a silky potato soup.
- Butter – I like to use butter to melt and caramelize the onions.
- Onion – A finely minced onion works best for this recipe. The thicker the onion the more that you will tell it’s present in the soup.
- Flour – Once the onions are caramelized you’ll make a roux with the flour to help thicken the soup.
- Milk – I use straight 2% milk for this recipe. This gives the potato soup a creamy texture!
Directions
In a large stock pot melt butter on medium heat.
Then add in onion. Caramelize until golden brown mixing periodically, for 10 minutes.
Once the onions are golden in color add the all-purpose flour and mix well until the onions have been coated with the flour mixture.
Pour the milk into the pot and stir for one minute.
Then add in the mashed potatoes. Mixing until all the potatoes have broken up. Cook on medium-low heat for 10-15 minutes or until potatoes are smooth. Taste the soup and add salt and black pepper if desired.
Ladle into bowls and top with dried parsley, shredded cheddar cheese, crumbled bacon, and cracked black pepper. Enjoy!
FAQs
Some of my favorite things to pair with potato soup are the following:
-Dinner rolls
-Turkey Sandwich
-Ham Sandwich
–Salads
To thicken the potato soup you’ll simply want to make a roux of butter and flour. The more flour and butter you use the thicker the soup will be. In addition to the roux, you can add part heavy cream and half of the milk!
If you find the potato soup is too watery you’ll want to make a cornstarch slurry. Mix 2 tablespoons cornstarch with 1 tablespoon water until smooth. Begin stirring the soup, and gently pour in the slurry. Within in a minutes time you will notice the soup will begin to thicken. Taste the soup and season with additional salt and pepper as needed.
Tips & Tricks
Here are a few of my favorite tips and tricks I’ve found helpful when making this potato soup with mashed potatoes recipe.
- Toppings: You can top with green onions, chives, shredded cheddar, cracked black pepper, and my favorite bacon!
- Substitutions:
- Dairy Free – Omit the butter and milk and use a plant based alternative. Just know it will alter the taste of the soup.
- Gluten Free – Use a gluten free flour for the roux.
- Vegan – Omit the dairy for plant based alternatives and use a vegetable stock instead!
- Potatoes – You could make this a sweet potato soup if you have mashed sweet potatoes instead.
- Broth – If you don’t have milk you could use vegetable or chicken broth.
Leftover Recipes
If you find yourself with an influx of leftover holiday food you’ll love some of these easy recipes that pair well with my favorite mashed potato soup recipe!
Still looking for more leftover recipes? Check out my 40+ Thanksgiving leftover recipes roundup!
If you make this leftover mashed potatoes soup, I would be honored and love for you to take the time to leave a star rating and comment! I spend hours developing and testing these recipes, and always love to hear feedback and user experience!
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Mashed Potato Soup
Equipment
- Stove Top
Ingredients
- 2 tablespoons Salted Butter
- ½ small Onion diced
- 1 tablespoon All-purpose flour
- 2-½ cups 2% milk
- 3 cups Leftover mashed potatoes
- salt and pepper to taste
- 1 teaspoon Dried parsley
- ½ cup Shredded Cheddar Cheese
- 4 slices Cooked Bacon diced
Instructions
- In a large stock pot melt butter on medium heat.2 tablespoons Salted Butter
- Then add in onion. Caramelize until golden brown mixing periodically, for 10 minutes.½ small Onion
- Once the onions are golden in color add the all-purpose flour and mix well until the onions have been coated with the flour mixture.1 tablespoon All-purpose flour
- Pour the milk into the pot and stir for one minute.2-½ cups 2% milk
- Then add in the mashed potatoes. Mixing until all the potatoes have broken up. Cook on medium-low heat for 10-15 minutes or until potatoes are smooth. Taste the soup and add salt and black pepper if desired.3 cups Leftover mashed potatoes, salt and pepper to taste
- Ladle into bowls and top with dried parsley, shredded cheddar cheese, crumbled bacon, and cracked black pepper. Enjoy!1 teaspoon Dried parsley, ½ cup Shredded Cheddar Cheese, 4 slices Cooked Bacon
Video
Notes
- Toppings: You can top with green onions, chives, shredded cheddar, cracked black pepper, and my favorite bacon!
- Substitutions:
- Dairy Free – Omit the butter and milk and use a plant based alternative. Just know it will alter the taste of the soup.
- Gluten Free – Use a gluten free flour for the roux.
- Vegan – Omit the dairy for plant based alternatives and use a vegetable stock instead!
- Potatoes – You could make this a sweet potato soup if you have mashed sweet potatoes instead.
- Broth – If you don’t have milk you could use vegetable or chicken broth.
HollyRae
Thank you for this great recipe! I had leftover mashers and needed a quick soup for an afternoon snack for some elders. And this was quick! I did make 2 tiny changes (used EVOO and had a mirepoix mix instead of onion) and did add some chicken broth to stretch it (as you suggested) but am very grateful for the base recipe and it …was …delicious! and got comps from the recipients.
Katie
HollyRae, I love everything you changed to the recipe. Glad that they all enjoyed it!
Doris
Another well deserved 5 star rating! I made this @ 6 am and it will be my breakfast and lunch. Minor changes included addition of some fresh garlic because I love garlic and used some bacon grease in addition to butter. Thanks for sharing.
Katie
Doris–so happy to read another fantastic review! I love the bacon grease and garlic addition!
Cee
Added onion salt, a little sharp cheddar, a little Parmesan and some chopped bacon in the soup. Then topped with bacon, cheddar and green onion really tasty..
Katie
Cee–love your additions to the soup!
Debra Mulvaney
I used left over ham after onions glazed. Ham left over from Thanksgiving dinner. Absolutely perfect so far. added a pinch of garlic pepper salt. thank you for this recipe
Katie
Debra, so happy to read you loved this recipe and I love the addition of ham!
Katie Nye
We had a community Thanksgiving dinner on Saturday and I was tasked with the mashed potatoes. I was instructed to make 30 lbs of potatoes. Turned out that we actually needed about 12 lbs. Guess who ended up with 18 pounds of leftover mashed potatoes.
I found this recipe and it’s amazing. Thank you for sharing. 3 cups down. I’m on the hunt for more recipes.
Katie
Katie–oh my goodness that’s a lot of leftover mashed potatoes. So glad you enjoyed this recipe. You can freeze mashed potatoes too! Here is a roundup of other ways to use up leftover mashed potatoes! Hope you find some more delicious recipes.
AndreaZW
The weather in Michigan is getting cool enough to start making soup! This was the first one of the season. We loved it!
Katie
Andrea, this is great to read! The best way to use up leftover mashed potatoes!
Debbie
I just made this soup for one. oh my so good. I wish I had another bowl.
Katie
Debbie — so happy to read you loved this! It’s the best way to use up leftover mashed potatoes. Thank you for taking the time to leave a comment and review. 🙂
Thomas P Myrick
Really really good
Lucinda Meyer
Good recipe but as it cooked I tasted it and it needed seasoning. I threw in some minced garlic the last 4 minutes the onions cooked. I seasoned liberally with pepper and salt to a lesser extent. I stirred in finely chopped smoked gouda toward the end of cooking. I used half and half because that’s what I had and the soup was creamy. I used a package of Bob Evans garlic mashed potatoes that was in the fridge. The flavor and consistency was excellent. Quick to put together, tasty, filling. I served it with a spinach/beet/goat cheese salad and sourdough bread. It got rave reviews and requests to make it once a month.
Katie
Lucinda–love your additions to the soup. Glad that it was a hit and will now be a go-to recipe!
Jess
Threw this together this morning for my son to take for lunch. Was short on time so I used onion powder. I also used some cream, half and half and milk to use up what we had. I also added a heaping teaspoon of chicken base. It was a little thin, so I added a dash of potato flakes. I think it was great- sure smelled awesome and he said the spoon he tasted before he left was great.
Really I wanted to say thank you for putting the amounts of ingredients below each step. It drives me nuts to have to keep scrolling up and down to find out how much of xyz I need to add. I don’t understand why more people don’t do this. Thank you!
Katie
Hi Jess, thank you so much for taking the time to leave a 5 star comment. I get mixed reviews about putting the amounts of ingredients under each step. Some love it and some find it even more confusing.
Traci McDonough
Super recipe! (Pun intended…) I had some garlic mashed potatoes with cheese in them that were leftover and worried the cheese might somehow mess things up but it melted nicely and the overall result was delicious! I also really liked how simple this was to prepare, an added bonus that makes this a recipe I’ll be using again. Often!
A side note: my husband enjoyed it very much, too and he’s a picky eater so that’s saying something. Thank you for sharing your recipe!
Katie
Traci! I’m so happy to read this. I love how versatile this recipe is and works with basically all mashed potatoes!
McG
Easy, Filling, and a great way to use up those extra mashed potatoes.
Katie
Thank you so much for taking the time to leave a 5 star review! Yes, the best way and only way to use up the extra mashed potatoes!
Ruthann
I have about 2 cups (or so) of leftover mashed potatoes. I would like to use your recipe. I like some diced potato in my soup. Do you think if I cooked up 1 medium potato to put in that it would be too much?
Thanks.
Merry Christmas
Katie
Hi Ruthann, Apologize for the delayed response. I was on vacation. I think one medium potato would be fine! So many people have given a spin on this recipe and it always turns out delicious!
Debie
Holy f! I’m in love ❤️❤️❤️❤️
Katie
Thanks Debie so much for your 5 star review! So happy you love it!!!
Laura Sherrick
This soup is delicious!. This is the first time I’ve actually used my leftover mashed potatoes. I always mean to, but somehow they get buried deep in the fridge until it’s way too late. Never again. I made this pretty much exactly as written. A topping I added for myself is a dash of Tabasco. Yum! This goes into the ‘keeper’ file. Thank you.
Katie
Hi Laura, thank you so much for taking the time to leave a 5 star comment. I’m so happy you loved this recipe!
Kathy
This was delicious! I just made a batch and can’t wait to serve it. Great flavor and texture: it’s a warm hug in a bowl. I love potato-leek soup so I used about 1/2 cup chopped leeks instead of the onion. Recipe is definitely a keeper!
Katie
Hi Kathy, so happy to read this. Love the addition of leeks to the soup! Thank you for taking the time to leave a 5-star comment!
Kathie
I added some peas and carrots because my husband wanted veggies. My son loved the cheese and extra bacon. Everybody happy!
Katie
Kathie, I love all the customization’s you made for each family member! Thank you for taking the time to leave a 5-star comment!
Betty Kealy
made a small 1/2 batch. cooked bacon then onions until done added 1/8 teaspoon fresh chop garlic simmer for a minute added floor simmer 2-³ minutes. then added milk + little cream. mixed with immersion blender, added mashed potatoes, quick 2nd blend, heat until hot add cheese + salt/pepper – enjoy
Katie
Hi Betty, Thank you for taking the time to share your half batch tweaks! Sounds like it was delicious!
Carol
absolutely the best potato soup. I don’t care for onions but this recipe is so good it is OK by me
Katie
Carol, so happy to read you love this potato soup. Thank you for taking time to leave a 5 star review.
Wendie Williams
Used leftover KFC mashed potatoes, it was great!!
Katie
Hi Wendie, thanks for taking the time to leave a 5 star review. Glad it worked with KFC mashed potatoes!