Leftover Mac and Cheese Soup

Leftover Mac and Cheese Soup ~

Got leftover mac and cheese? Bring your favorite mac back to life by serving it in a whole new way!

Serve this creamy soup with a side of crusty bread, and dinner is done!

Mac and Cheese Soup Recipe

One of the best things about the day after Thanksgiving is all the leftovers, but let’s be honest; some hold up better than others. Stuffing Muffins, Dressings, and even the Green Bean Casseroles are all just as tasty the next day. 

Mac and cheese can be a different story. It’s just the nature of the dish. When left overnight in the fridge, pasta has a tendency to soak up whatever sauce it is sitting in. This can leave the dish drier overall, and, well, it’s just not as good as it was that first day.

When faced with leftover mac and cheese, the best thing to do is repurpose it. This macaroni and cheddar cheese soup is a great way to turn your leftover cheesy pasta dish into a new and delicious meal the whole family will love. 

This macaroni soup is rich, creamy, and ready to serve in about 20 minutes!

Ingredients for Leftover Mac & Cheese Soup

• 1/4 cup butter
• 1/4 cup yellow onion, finely chopped
• 2 teaspoons garlic, minced
• 1/4 cup all-purpose flour
• 4 cups chicken-style broth
• 2 cups cheddar cheese, shredded
• 4 ounces plain cream cheese
• 1/3 cup oat milk
• 1/4 teaspoon ground black pepper
• 4 cups prepared mac & cheese

Ingredient Notes

• Butter – Used for sautéing the onions and garlic, adding richness to the soup.
• Yellow Onion and Garlic – Adds savory flavor and texture to the soup base.
• All-Purpose Flour – Used as a thickening agent to give the soup its creamy consistency.
• Chicken-style Broth – The base of the soup; Better Than Bouillon’s No-Chicken Base works well as a vegan option for chicken broth.
• Cheddar Cheese – Adds a tangy, cheesy flavor. I used mild cheddar, but sharp cheddar cheese also works well. For a different flavor profile, cheddar can be swapped for mozzarella, Gouda, or whatever suits the style of your mac. 
• Cream Cheese – For a rich and creamy texture to the cheesy soup.
• Oat Milk – I like this dairy-free plank milk because it has a mild flavor that I find similar to dairy-based whole milk.
• Prepared Mac and Cheese – You will need leftover macaroni and cheese ready to go for this soup. 

How to Make Leftover Mac & Cheese Soup

STEP ONE: Set a large pot over medium-high heat and add the butter. When the butter is melted, add the onions. Saute onion for 2 minutes, until softened and fragrant.

STEP TWO: Add garlic and continue cooking for an additional 30 seconds.

STEP THREE: Whisk in the flour until incorporated; the mixture will be thick.

STEP FOUR: Gradually add the broth, whisking until the consistency is smooth.

STEP FIVE: Bring just to a boil, then reduce the heat to low.

STEP SIX: Add the cream cheese, cheddar cheese, milk, and black pepper to the pot. Stir frequently until the cheeses are melted.

STEP SEVEN: Add the prepared mac and cheese, stirring to distribute throughout the soup.

STEP EIGHT: Adjust seasoning to taste and serve hot.

Storage

• Let the soup cool to room temperature, then store it in an airtight container in the refrigerator. Gently reheat over low or medium heat before serving. 

More Easy Recipes You’ll Love!

• Vegan Creamy Macaroni and Cheese Recipe
• Easy Cheesy Tetrazzini
• Cheesy Cauliflower Soup
• Vegan Pub Style Beer Cheese Dip
• Cheesesteak Sloppy Joes

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Originally published on December 1, 2015. Updated May 10, 2024.