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Creamy Costco Rotisserie Chicken Soup with Mushrooms

Preview: This Creamy Costco Rotisserie Chicken Soup recipe is packed with leftover chicken and fresh mushrooms in a creamy white sauce thickened with mashed cauliflower. No grains or gluten

Are you a fan of the rotisserie chicken at Costco?  It’s cheap–4.99 for a plump 3-pound chicken.  It’s already cooked and well-seasoned with a combination of spices I have been unable to reproduce. PLUS: It’s grain-free and gluten-free.

No Costco nearby or you’re not a member? No problem. Use ANY rotisserie chicken for this recipe.

 The recipe is written for an Instant Pot. But if you want to make it on top of the stove, see the notes in the recipe below for details.

Costco  Rotisserie Chicken Soup in a bowl with crackers on the side

Kitchen Secret for thickening soup without flour or cornstarch:

Stir in some mashed cauliflower for a more hearty and chowder-like texture. The cauliflower taste is minimal. It’s an idea you might try if you want to eat more vegetables and lower carbs.

If you don’t care for cauliflower, you can always thicken this soup by adding 3-4 tablespoons of flour or cornstarch to the whipping cream. Add it to the soup and simmer until thickened.

How to make Rotisserie Chicken Soup:

A single rotisserie chicken at our house is good for at least 2 meals and a pot of bone broth.

The first will be straight off the bone, sliced, white meat. Best eaten it while it’s still hot. Use the remaining chicken meat in chicken salad, soup, or a one-dish meal.

  1. Make the mashed cauliflower using your instant pot. If you don’t have an Instant Pot, use this mashed cauliflower recipe to make it in your microwave. Set the cauliflower aside and proceed with the rest of the recipe as pictured below.

How to make broth with a rotisserie chicken carcass or bones:

Bone broth will include everything that’s left. Every bone, piece of skin and gristle, remaining bits of chicken, and gelatin left in the bottom of the chicken carrier will be utilized.

In case you’re wondering, bone broth is a regular stock that has been cooked for a prolonged period. This causes the gelatin from inside the bones to leak out into the stock. Notice how your stock gels when it is chilled.

broth made with Costo rotisserie chicken carcass

Before you make chicken stock, remove all the chicken meat you can from the bones.  Place the remaining bones and skin (with the wonderful but mysterious spices) into a slow cooker.

Don’t worry about the fat in the skin. Most of it has already melted away in the rotisserie process.

Next, clean out the vegetable drawerOnion pieces or limp green onions hanging around?  Check.  Dried out carrots–maybe even with some greenery growing out the top?  Check.  Celery with leaves in the middle you won’t be using in your salad?  Check. Grab a bay leaf, parsley or cilantro and add them, too. 

Finally, throw in a tablespoon of whole peppercorns. Barely cover the whole mess with water.

Set your slow cooker on Low for 12 to 24 hours.   When finished, pour bones and broth through a fine strainer. Refrigerate the broth for up to five days or freeze.

More recipes for soup lovers:

Did you enjoy this recipe? If so, you can help others and me by leaving a 5-star 🤩 rating inside the recipe below. No comments are required.

Hope to see you again soon!

p.s. If you have any questions or suggestions, you can email me privately: Paula at

Yield: 5 servings

Costco Rotisserie Chicken Soup Recipe

Chicken and Mushroom Chowder

Leftover rotisserie chicken finds new life in this well-seasoned creamy soup full of chicken and veggies including mushrooms and carrots.

Prep Time 20 minutes
Cook Time 5 minutes
Total Time 25 minutes


  • 1 small head of cauliflower
  • 2 tablespoons vegetable oil
  • 1 cup chopped onions
  • 2 stalks celery
  • 4 ounces sliced mushrooms
  • 3 medium carrots
  • 3 cups chicken broth or bone broth (see recipe below)
  • 1/4 teaspoon white pepper
  • Salt and freshly ground black pepper to taste
  • 1/8 teaspoon crushed red peppers
  • Fresh thyme, several sprigs or 1/4 teaspoon dried thyme
  • 1 teaspoon poultry seasoning
  • 1 to 1-1/2 cup cooked chicken, finely diced
  • 1/2 whipping cream
  • 1 tablespoon chopped parsley


  1. Pour 1 cup water into your Instant Pot, then add a steamer basket. Remove the core from a head of cauliflower and break or slice it into small pieces. Set Instant Pot to High Pressure for 5 minutes. Use a quick-release (throw a towel over the lid and open the vent). Remove cauliflower to a food processor or a medium bowl and mash it until fairly smooth. Set aside.
  2. Empty the water and remove the steamer basket from Instant Pot. Heat 2 tablespoons of oil in a pressure cooker. Sauté onions and celery until tender.
  3. Add sliced mushrooms and continue cooking.
  4. Add remaining ingredients except for whipping cream and parsley.
  5. Cook on High Pressure for 5 minutes. When complete, use a quick release. Add 1-1/2 to 2 cups mashed cauliflower and stir.
  6. Garnish with chopped fresh parsley just before serving.


How to Make on the Stove:

Heat oil in large soup pot over medium heat on top of the stove. Add onions and celery and cook until softened but not browned. Add remaining ingredients except chicken, cream, and parsley. When vegetables are soft, add remaining ingredients, including mashed cauliflower, and heat another 5 minutes. Garnish with chopped parsley.

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Nutrition Information:



Serving Size:

1 bowl

Amount Per Serving: Calories: 224Total Fat: 13gSaturated Fat: 3gTrans Fat: 0gUnsaturated Fat: 9gCholesterol: 45mgSodium: 781mgCarbohydrates: 14gFiber: 4gSugar: 7gProtein: 15g

Did you make this recipe?

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Monday 25th of November 2019

I love how you wrote the instructions for making chicken broth on this post. Such carefree cooking. It's a great way to make broth and I wanted to thank you! I have made it a number of times and currently have a batch simmering--the house smells so marvelous and cozy! Hope you have a great holiday this week, Paula!


Monday 25th of November 2019

I couldn't agree more about the way making chicken broth makes your house smell. Makes any day smell like Thanksgiving. Thanks for writing, Julie.


Saturday 20th of October 2012

Love the idea of making broth from the chicken. I made the recipe and love it. Thanks for your creative ideas.


Monday 19th of October 2009

i second that on the costco chickens. yummy! irresistable.


Thursday 1st of October 2009

I have boiled these bones/skin/etc. in water up to 3 times! It's amazing how much flavor you can extract.

Ann Hastings

Tuesday 29th of September 2009

Love rotisserie chickens, we get ours from Tom Thumb (where we shop)- but Costco ones are great too! I make chicken & sour cream enchilladas out of the chicken... yummy!

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