Apple ‘n Onion Chicken Casserole {keto, paleo, Whole 30}

apple 'n onion casserole with spoon in pan
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Apple ‘n Onion Chicken Casserole is sure to be one of your new favorite comfort foods that even the pickiest of eaters will love!

This is one of our go-to recipes for lunches since it is a one dish meal, making it easy to take to work in a medium sized glass container or jar. 

Apple ‘n onion chicken casserole is also perfect for making ahead of time for an easy meal to grab out of the freezer.

So grab some of that cheap acorn squash on sale in the fall and let’s get cooking!

bowl with spoon and pan of of apple 'n onion chicken casserole

Is Acorn Squash Healthy?

Let’s take a look at the health benefits of acorn squash.

Acorn squash is full of vitamins, especially vitamin C, vitamin A, and a range of B vitamins.

There are also a variety of minerals in acorn squash, including potassium, magnesium, iron, and manganese.

Acorn squash is full of antioxidants which are critical for cellular healing.

In fact, winter squashes are right behind carrots as the the second densest food for α-carotene!

And did you know that α-carotene is actually able to inhibit the growth of cancer cells better than β-carotene?

As if that wasn’t appealing enough, acorn squash also boasts of benefits such as boosting immunity, improving your vision, aiding in skin health, and more!


Acorn squash is full of some good stuff!!

spoon lifting apple 'n onion chicken from casserole dish

Is Acorn Squash Keto-Friendly?

But even with all of the good things that are found in acorn squash, does acorn squash fit into a keto lifestyle?

It really comes down to how strict your macros are, if you go by net carbs or total carbs, and how much acorn squash you use in this recipe.

One cup of cooked acorn squash has 30 grams of carbs in it, with 9 grams of fiber.

This recipe calls for one acorn squash that is about 2 pounds, which should yield around a cup and a half of cooked, mashed acorn squash.

That brings the total carb count for the acorn squash to 45 total grams, or 31.5 net carbs for the entire casserole.

Divide by 8 servings and you are looking at 5.6 grams of total carbs per serving, or about 4 grams of net carbs per serving.

For my family, that fits into our diet and allows us to still reap the health benefits of acorn squash.

Only you can decide if acorn squash fits into your keto macros for the day! (keep reading for substitutions and add-ins for keto!)

casserole dish of apple 'n onion chicken partially eaten with spoon in pan

Can I Use Something Besides Acorn Squash?

For those on a strict keto diet or if you don’t like acorn squash, don’t worry!

The acorn squash in this recipe can easily be swapped out with mashed cauliflower!

Mashed cauliflower has about 5 grams of carbs per cup and 3 grams of fiber.

You can see why cauliflower is the vegetable of choice when it comes to low-carb diets.

I just like a little more variety in my diet than cauliflower every time I want to make a casserole, which is why I sparingly enjoy adding squash to my diet in the winter.

Now, I’m not sitting down to eat half an acorn squash in one sitting as some stuffed squash recipes make it look like.

As a thin layer as the base of this recipe, acorn squash is a nice change from cauliflower.

But you do you!

If you are just adapting to the keto diet or still have a long way to go in your weight loss journey, by all means, substitute the acorn squash with cauliflower.

It’s so easy – just replace the acorn squash with one head of cauliflower that has been steamed and mashed.

Make the prep time faster by buying frozen cauliflower or already prepared mashed cauliflower!

Just check to make sure the prepared mashed cauliflower doesn’t have any other hidden ingredients in it!

And be sure to add the extra butter that I mention in this next section on how to make this casserole even more keto-friendly!!

spoon holding up apple 'n onion chicken casserole

How to Make Keto-Friendly Apple ‘n Onion Chicken Casserole

As we just discussed, this recipe is already fairly keto friendly, but there are some extra steps that I would use to increase the fat per serving and lower the carb count per serving.

Sub the Acorn Squash with Cauliflower

I covered this in detail above but just as a reminder, you can sub the acorn squash with one head of cauliflower, cooked and mashed (with more butter of course!)

Halve the Apples

Use 1 chopped apple instead of 2.

This will help lower the carb count without altering the flavor.

Use Chicken Thighs

Consider using uncooked, cubed chicken thighs instead of Instant Pot cooked and shredded chicken breasts to increase the fat content.

You will lose a lot of the fat if you cook the chicken in the Instant Pot!

Chicken thighs also have more than double the fat of chicken breasts!

Add More Butter!

Another way to help increase the fat content is to liberally add butter to the acorn squash (or cauliflower if you are going that route!).

And when I say liberally, I mean like another 4 to 8 Tablespoons of butter!

That will increase the “liquid” in the dish, so I would consider halving the broth if you add 4 Tablespoons of butter.

If you add the full 8 Tablespoons of butter, consider leaving the broth out altogether the first time you make it.

My husband doesn’t like runny dishes, so I always err on the thick side!

Plus, it’s easier to add liquid than remove it!

Add Some Cheese!

This recipe doesn’t call for cheese, but that doesn’t mean you can’t add any!

Add 8 ounces of shredded cheddar cheese on top.

You will want to also plan an extra 5 minutes to put the casserole dish in the oven and broil the top until the cheese is melty and starting to get those beautiful brown spots on top.

close up of apple 'n onion chicken casserole dish

Do I have to Use Shredded Chicken?

Of course not!

I hate getting into a recipe and it’s assumed that I already have some of the ingredients cooked and on-hand.

Most of my recipes include shredded chicken for two reasons:

  1. It’s our preferred way to eat chicken. Shredded chicken is easy for our daughter to eat and it spreads out nice in a casserole.
  2. I tend to just run big batches of chicken in the Instant Pot. I use some of it right away in a dish and then I save half for later in the freezer to make meal prep faster the next time. That means that I usually have some shredded chicken ready in the freezer!

But if you don’t have the freezer space to keep shredded chicken on hand, or if you like cubed chicken breasts or thighs instead, do that!

I have notes in the directions for both shredded and cubed chicken.

bowl and pan of apple 'n onion chicken casserole with bowl of broccoli

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casserole dish partially eaten with spoon in pan

Apple ‘n Onion Chicken Casserole {keto, paleo, Whole 30}

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  • Author: Monster Cookie
  • Total Time: 45 minutes
  • Yield: 9 servings 1x


Warm and hearty, this apple ‘n onion chicken casserole is an irresistible fall family favorite that even your pickiest eaters will enjoy!


  • 1 acorn squash (about 2 pounds) – OR 1 head cauliflower steamed and mashed for even lower carb (see above!)
  • 4 Tablespoons butter (or 2 Tablespoons avocado oil for paleo)
  • Optional: more butter stirred in with the squash for keto (see above for tips)
  • 6 cloves of garlic, minced (or 1 teaspoon garlic powder) 
  • 1 medium onion, chopped (or 1 teaspoon onion powder) 
  • 2 pounds cooked, shredded chicken, or uncooked, cubed chicken  
  • 2 Granny Smith apples, chopped (only use 1 for keto)
  • 2 teaspoons salt  
  • 2 Tablespoons Italian seasoning 
  • ¼ teaspoon cayenne pepper (optional)
  • ¼ cup coconut aminos 
  • ¼ cup apple cider vinegar 
  • ½ cup vegetable broth or chicken bone broth 
  • (Optional) Top with cheese and/or chopped green onions


  1. Cut the acorn squash in half, scoop out the seeds, and place in the Instant Pot. Add 2 cups of water. Put on the lid and set the Instant Pot to pressure cook for 6 minutes. Once the squash is done cooking, place a wash cloth over the vent and quick release the steam. If you don’t have an Instant Pot, wash the squash and place in the oven and cook at 350 degrees for 45 minutes to 1 hour (or until soft when pierced with a knife). Let the squash cool off while the rest of the food cooks.
  2. While the acorn squash cooks, prepare the onion and garlic (if not using powder), chop the apples, and cube the chicken if you are going that route!
  3. In a large pot, melt the butter. Once melted, sauté the onion and garlic for about 5 minutes or until fragrant. 
  4. Add the chicken, chopped apple, salt, Italian seasoning, and cayenne pepper and cook for 5 more minutes (or longer if chicken was uncooked). 
  5. Add the remaining ingredients and stir to combine.
  6. Use a spoon to scoop out the squash from the skin. Mash the squash into the bottom of a casserole dish. If using the additional butter, I recommend stirring it into the warm squash.
  7. Spread the apple ‘n onion chicken mixture on top.
  8. If serving with cheese, broil in the oven until cheese is melty and turning golden brown. This is about 5 minutes in my oven but every oven is different so keep a close eye on it!
  9. Top with green onion if using. 


Storage: Keep in the fridge for up to 5 days.

Freezing: This casserole is great to make ahead of time and freeze! Freeze for up to 6 months for best taste/freshness, but it can be stored safely longer than that.

  • Prep Time: 30 minutes
  • Cook Time: 15 minutes

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