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.
wendy
I made this for my family for lunch today. So delicious! My boys are big eaters as well as my husband takes leftovers for lunch so I also added 3 cups of chicken broth and cut up 4 small potatoes to increase the amount of servings. It turned out great! We topped with shredded, triple cheddar cheese and bacon.
Katie
Wendy, sounds like perfect additions to the soup! Glad everyone enjoyed the potato soup as much as I do!
Krista
We just made this soup. We used bacon grease instead of butter. We also added garlic and onions and caramelized them
together. The soup is amazing and simple thank you. Great idea to use up your mashed potatoes.
Katie
Krista, I love all your additions to the soup! Thank you for taking the time to share with others. 🙂
Mary
This recipe was super simple and delicious! I let it simmer longer than the recipe indicated to thicken a bit more and added crushed red pepper and garlic powder. Excellent use of leftover mashed potatoes, or in my case the discarded portion of my New Year’s Eve potato skins.
Katie
Mary–sounds delicious! Thank you so much for sharing your additions this delicious recipe!
Linda
This is amazing and so easy to make. thanks you Katie
Katie
Linda, so happy to read you loved this soup recipe.
Jessica
So easy to make! I only had a cup of mashed potatoes and some whole milk, so I just shrunk the recipe. Doesn’t have to be exact to turn out great. Topped it with chives as well. Super easy and done in under 10 min. Delicious comfort food on a cold day!
Katie
Jessica– so happy to read you loved this recipe and that you were able to make the proper modifications. That is what I love most about this recipe! Thank you for taking the time out to leave a 5 star review!
Kim
Delicious!!!
Katie
Kim, so happy to read you loved this recipe! Thank you for taking the time out to leave a 5 star review!
Diane
Was a wonderful way to use up leftover mashed potatoes. Made it as written. Only added a dash of garlic powder as my family likes garlic on about everything.
Katie
Diane, so happy to read you loved this recipe and love your additions to the recipe! Thank you for taking the time out to leave a 5 star review!
Jennifer
I just made this and it came out so good! I added a dash of garlic powder and some evaporated milk I also had leftover. Topped it with cheddar, green onions, and crisp bacon. Will be recommending this to everybody! Thank you!
Katie
Jennifer, Your additions to the soup sound delicious. I truly appreciate your recommending this to others and thank you for taking the time out to leave a 5 star review!
Itzpa Rau
How you make your original mashed potatoes influences the soup. Our mashed potatoes were really dense so we added pasta water to thin out the soup. Also, didn’t have an onion on hand so we substituted onion powder in the rue. Whole family thought it was delicious! Smart recipe Katie. Thank you!
Katie
Hi, Yes, I totally agree the thickness of your original mashed potatoes will depend on the soups consistency! I’m glad you enjoyed this recipe!
Kimberly decicco
Just used your delicious recipe! Thank you..It’s so delicious. I added chopped ham also as I had that leftover with the mashed potatoes and 2 fresh shucked ears of corn. It came out like a delicious im
Katie
Kimberly–I love all the additions you made! So happy you enjoyed this recipe.
Julie K Hurford
Very helpful and delicious base recipe! My doctored version: leftover Colcannon mashed potatoes, sautéed onions, 1 minced garlic clove, frozen corn kernels, half a Polish dinner sausage (browned and crumbled), water, bone broth mix, a teaspoon of white miso, and black pepper. Great result. Thank you for sharing this recipe – the idea of plowing through all those potatoes was a little sad. Much more fun as a soup.
Katie
Hi Julie, thank you so much for taking the time to leave a 5 star comment! I love all of your additions to the soup. Sounds delicious!
DQ
This turned out really well. I had leftover regular & smoked loaded mashed potatoes to use up & this was the perfect recipe. I upped the mashed potatoes to thicken the soup, which became more of a chowder.
Katie
Hi, thanks for taking the time to leave a 5 star comment and review. So happy to read you enjoyed this recipe–it’s one of my favorite ways to use up leftover mashed potatoes. Next time you have leftover mashed potatoes give my potato cakes recipe a try!
Jennifer I
This is a very simple, excellent recipe. Mmmmm ty!
Katie
Hi Jennifer, thank you so much for taking the time to leave a 5 star comment! So happy to read you like this recipe as much as I do!
Joan Buckley
Great recipe – love it!
Isn’t your last name Polish?
Why not “katieskuchnia” ?
I grew up with many Polish people in Manchester NH & always loved the meals I shared with them. I still make many Polish dishes!
Katie
Hi Joan, thank you for taking the time to share. My father in-law said that years ago! lol I married a Polish man; however, I am part Polish but also Italian! Hence the “cucina”!
Amanda
Hi Katie!! This mashed potato soup looks so easy, I had to share it on my blog today. I was compiling a list of things to do with left over mashed potatoes and your soup was first on my list!! 😀
Katie
Thanks Amanda! Yes–so good!!!
Jennifer
So good, the picky kids LOVED it!
Katie
Jennifer that’s great to read! Glad you and your family enjoyed it.
Nutmeg Nanny
Mashed potatoes and soup, oh my thats a dream! I love it 🙂
Katie
Mine too! 🙂
Kelly Foy
Made this tonight with left overs from Christmas.. Our mashed potatoes were originally made with Philadelphia Savoury Garlic Cooking Cream. Amazing.. And so fast! Pinned it!
Katie
Kelly so glad you loved it! I’ll have to make it with the Philadelphia Savory Garlic Cooking Cream next time! 🙂
Kayle (The Cooking Actress)
I NEED to try this! Pinning!
Genie Robbins
I love homemade potato soup but have never tried it with mashed taters. Sure looks easy!