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.
Pat G
Serve with Sherry as a condiment at the table
Susan
Very good and very delicious. Glad to use up the mashed potatoes.
Katie
Susan, glad you were able to use up the leftover mashed potatoes. Thanks for taking the time to leave a comment.
Kathy Oshiro
Exactly what I was looking for! Delicious, simple, quick, & made with ingredients that are on hand; loved it! I added a cup of cooked chopped broccoli to add nutritional value. In the end my soup was too thick so I drained the grease from the pan I had fried the bacon in & deglazed the pan with about 1/2 C of water & added to the soup. Since I will be freezing the leftovers (I’m a family of one), I added all the cheese & bacon bits to the soup before serving. Again, simply delicious! Thank you!
Katie
Kathy, I’m so happy to read you loved this recipe and I love the addition of adding broccoli!
Shanna
Made this tonight with leftover mashed potatoes from Thanksgiving that I had frozen. Ran it through the blender after cooking to remove the grainy texture from the frozen potatoes, and the resulting texture was lovely and smooth.
Next time we’re going to add some parmesan or sour cream to add a little “sharpness” to the flavour.
Highly recommend, will definitely make again.
Katie
Shanna, so glad you enjoyed this recipe. It’s so easy and delicious (and very customizable)!
Michelle
I just had dental work done and very picky eater the only soup I like is potatoe soup. Not having many ingredients on hand and it being extremely cold out side I started searching on line for recipes. Although I made mashed potatoes fresh for this it was the perfect meal I needed while I can’t chew at the moment. This is now a favorite.
Katie
Michelle, first off, I hope you heal quickly. I’m so glad you enjoyed this recipe. It’s the most perfect way to use up leftover mashed potatoes, too!
Lisa
I had leftover steamed carrots with fresh dill that I tossed in…thinned it a bit with chicken bone broth. Absolutely delicious! I don’t know why this never occurred to me over the years. I’ve done everything else with leftovers mashed, but this was so quick and gratifying!
Highly recommend!
Katie
Lisa, sounds like a great addition! Yes–perfect and EASY way to use up leftover mashed potatoes.
Mack
I had leftover mashed potatoes and this recipe was perfect. . I used plant based butter and almond milk with a little Mrs Dash. Delicious! I sprinkled chives and used almond milk mozzarella cheese – sooooo good! Thank you so much!
Katie
Hi Mack, thanks for taking the time to share your plant based alterations to the recipe. I know this will help others who find this recipe and want to make it. I’m glad you enjoyed it!