Creamy 30-Minute Mashed Potato Soup
Mashed potato soup takes leftover spuds and turns them into a velvety bowl of comfort, ready in about 30 minutes.
It tastes like a loaded baked potato in soup form: rich, cheesy, and topped with crispy bacon, scallions, and a swirl of sour cream.
Why This Soup Wins Weeknights
This soup is my favorite way to rescue leftover mashed potatoes from the back of the fridge. The potatoes thicken the broth so nicely you do not need any roux or slurry.
A handful of sharp cheddar melts in at the end, giving it a tangy, creamy finish that never feels heavy.
Ingredients
- 3 cups leftover mashed potatoes: cold, straight from the fridge works great
- 2 tbsp unsalted butter: or bacon fat for extra flavor
- 1 medium yellow onion, diced: white or sweet onion also fine
- 3 cloves garlic, minced: use fresh for the best savory base
- 3 cups chicken or vegetable broth: low-sodium so you can control the salt
- 1 cup whole milk: half-and-half or heavy cream if you want it extra rich
- 1 cup shredded sharp cheddar cheese: plus more for topping
- 1/2 tsp kosher salt, plus more to taste: adjust based on how seasoned your potatoes are
- 1/4 tsp freshly ground black pepper
- Toppings: 4 strips cooked bacon, crumbled; 2 scallions, thinly sliced; 1/4 cup sour cream
Variations / Substitutions
- Make it vegetarian: use vegetable broth, skip bacon, top with smoked paprika.
- Dairy-free: swap milk for unsweetened oat milk, use a plant-based cheddar or 2 tbsp nutritional yeast for cheesy flavor, and skip the sour cream or use a dairy-free version.
- Protein boost: stir in shredded cooked chicken or diced ham with the broth.
- Spice it up: add a pinch of cayenne or a dash of hot sauce with the milk.
If you like this, try our Classic Baked Potato Soup next.
How to Make Creamy Mashed Potato Soup
Step 1: Sauté the Aromatics
Melt the 2 tbsp butter in a large pot or Dutch oven over medium heat. Add the diced onion and a pinch of salt; cook, stirring occasionally, until soft and translucent, about 5 minutes. Stir in the 3 cloves minced garlic and cook for 30 seconds until fragrant.
Step 2: Simmer the Soup Base
Pour in the 3 cups broth and add the 3 cups leftover mashed potatoes. Use a whisk to break up the potatoes as they heat, stirring until they dissolve into the broth.
Bring to a gentle simmer, then reduce the heat to medium-low and let it bubble softly for 10 minutes, until the soup is smooth and hot all the way through. The kitchen will smell like a baked potato at this point.
Step 3: Blend to Your Liking
For a completely smooth soup, use an immersion blender right in the pot and blend until no lumps remain, about 1 minute.
You can also leave it chunky if you prefer a rustic texture, or transfer half to a blender, purée, then stir it back in for something in between.
Step 4: Stir in the Cheese and Milk
Turn the heat to low. Pour in the 1 cup whole milk and sprinkle in the 1 cup shredded cheddar. Stir constantly until the cheese melts completely and the soup is silky, 2 to 3 minutes. Do not let it boil or the dairy can break and make the soup grainy. Taste and adjust with salt and pepper.
Step 5: Ladle and Load Up the Toppings
Ladle the hot soup into bowls. Top each serving with crumbled bacon, a shower of scallions, a dollop of sour cream, and a little extra cheddar if you like. Serve right away while it is steaming and the cheese pulls are still loose.
A Few Things That Make This Soup Even Better
- Use cold mashed potatoes. They are easier to break apart and less likely to make the soup gluey than warm, freshly mashed potatoes.
- If your mashed potatoes are very thick, add an extra splash of broth to thin the soup before you blend.
- Do not skip the low heat when adding dairy. Boiling after the milk and cheese goes in can cause the soup to separate.
- For deeper flavor, let the butter brown slightly before adding the onion — it adds a nutty note.
Storing and Reheating Leftovers
- Refrigerate: Cool completely, then store in an airtight container for up to 4 days.
- Reheating: Warm gently in a saucepan over low heat, stirring often. If the soup has thickened, thin it with a splash of milk or broth.
- Freezing: The soup can be frozen before adding the cheese and milk; save those ingredients for the day you reheat. If you freeze the fully made soup, the texture may be a bit grainy but still tastes fine when whisked well during reheating.
What To Serve With This Soup
Pair it with thick slices of toasted sourdough or a grilled cheese sandwich for dipping. A crisp arugula salad with lemon vinaigrette cuts through the richness. For a heartier meal, serve alongside roasted broccoli or a simple baked chicken breast.
Frequently Asked Questions
Can I use instant mashed potatoes?
Yes, but the soup will have a less complex flavor. Prepare the instant potatoes according to package directions, then use 3 cups for the recipe. Taste as you go and adjust seasoning.
Can I make this soup ahead of time?
You can make the soup through Step 3 and refrigerate for up to 2 days. Reheat gently, then complete Steps 4 and 5 right before serving for the creamiest result.
Is this soup gluten-free?
Yes, as long as your broth is gluten-free and your mashed potatoes are made without flour, the soup contains no wheat. Always double-check packaged broth.
What other cheese can I use?
Any good melting cheese works: Gruyère, smoked gouda, or a mix of cheddar and Monterey Jack all taste great.
Creamy Mashed Potato Soup Recipe
Ingredients
Method
- Melt butter in a large pot over medium heat. Sauté onion and a pinch of salt until soft, about 5 minutes. Stir in garlic and cook 30 seconds.
- Pour in broth and add mashed potatoes. Whisk until potatoes dissolve. Bring to a gentle simmer and cook 10 minutes.
- Blend with an immersion blender until smooth, about 1 minute, or leave chunky if you prefer.
- Reduce heat to low. Stir in milk and cheddar until melted, 2 to 3 minutes. Do not boil. Adjust salt and pepper.
- Ladle soup into bowls and top with bacon, scallions, sour cream, and extra cheese. Serve immediately.
Notes
